JP2023134866A - Servo system, and motor - Google Patents

Abstract

To construct a compact servo system while keeping a favorable servo control environment for a motor.SOLUTION: A control device for a servo system includes a first communication part configured to transmit/receive s signal with a motor through wireless communication, and a position/speed control part for performing control loop calculation regarding the position and speed based on a command value to the motor and a first signal which is a feedback signal regarding the operation of the motor and outputting the calculation result to motor side through the first communication part. The motor includes a second communication part configured to transmit/receive a signal with the control device through the wireless communication, a driver circuit for generating a drive current for the motor, and a current control part for performing control loop calculation regarding the drive current based on the calculation result outputted by the position/speed control part and received by the second communication part and a second signal which is a feedback signal relating to the drive current for the motor in the driver circuit and outputting the calculation result to the driver circuit.SELECTED DRAWING: Figure 1

Description

The present invention relates to a motor and a servo system including the motor and a control device.

In a typical servo system, a servo driver that drives a motor performs control loop calculations regarding position, speed, and current. A position command is issued to the servo driver from a higher-level control device (for example, PLC, etc.). Here, for example, in the technology of Patent Document 1, in order to provide a positioning device that realizes a robust position control loop in a servo system that servo-controls a plurality of control axes, a servo driver corresponding to the motor of each control axis is provided. A configuration is disclosed in which a controller that performs control loop calculations regarding current is placed in the driver, and a controller that performs control loop calculations regarding the positions and speeds of all axes is placed in a higher-level device of the driver. Furthermore, Patent Document 2 states that in order to improve reliability against failures, the circuit board that constitutes the position control loop and speed control loop, and the power module that includes the current control loop are separated inside the servo driver. The technical ideas that constitute it are disclosed.

Japanese Patent Application Publication No. 2007-73008 Japanese Patent Application Publication No. 2009-247207

Generally, a servo system includes a control device such as a PLC, a servo driver that generates a drive current for driving a motor according to a position command received from the control device, and a motor. In addition to a drive circuit (such as an inverter device) for generating current, the servo driver incorporates a functional unit that performs control loop calculations for servo control in the system. That is, the servo driver is also a device in which control signals and drive current are aggregated, and a large number of cables are connected to the servo driver. Therefore, when constructing a servo system, sufficient consideration must be given to the arrangement of the servo drivers. In particular, in a servo system for driving a plurality of control axes, servo drivers are required for the number of control axes, and the volume occupied by the servo drivers also increases.

Furthermore, in order to safely servo control the motor, it is necessary to suitably arrange a functional unit that performs control loop calculations for servo control in the servo system. In particular, if the functional section is located away from the motor to be controlled, there is a risk that servo control will be hindered accordingly.

The present invention has been made in view of such problems, and an object of the present invention is to provide a technique for constructing a servo system compactly while suitably maintaining a motor servo control environment.

A servo system according to one aspect of the present disclosure includes a control device and a motor. The control device includes a first communication unit configured to send and receive signals to and from the motor via wireless communication, a command value to the motor, and a feedback signal related to the operation of the motor. and a position/speed control unit that performs a control loop calculation regarding position and speed based on the first signal and outputs the calculation result to the motor side via the first communication unit. The motor includes a second communication unit configured to send and receive signals to and from the control device via wireless communication, a drive circuit that generates a drive current for the motor, and the position/speed control unit. Performing a control loop calculation regarding the drive current based on the calculation result outputted and received by the second communication unit and a second signal that is a feedback signal related to the drive current of the motor in the drive circuit, and a current control section that outputs the calculation result to the drive circuit.

In the servo system configured in this manner, a position/speed control unit that performs control loop calculations regarding position and speed related to servo control of the motor is arranged in the control device. On the other hand, a current control section related to servo control of the motor and a drive circuit (for example, an inverter device, etc.) that generates a drive current for the motor according to the calculation result of the current control section are arranged in the motor. As a result, unlike the prior art, the servo driver itself including the position/speed control section, current control section, and drive circuit can be omitted, so that the servo system can be constructed compactly. In addition, since signals are exchanged between the control device and the motor by wireless communication between the first communication section and the second communication section, it is possible to use a cable for signal transmission for servo control. The load required to construct the servo system can also be reduced.

Further, as described above, in the servo system disclosed in the present application, among the configurations corresponding to a conventional servo driver, a current control section and a drive circuit, which are functional sections related to current control, are arranged on the motor side. This means that among the functional units for servo control, a part that has the strongest influence on the behavior of the motor is placed close to the motor that is the drive target. As a result, although it is difficult to perform precise control compared to servo control using complete functional units including function units related to position and speed, it is sufficient for simple control such as stopping or continuing motor operation. Can be guaranteed. Therefore, the arrangement of the current control section described above makes it possible to construct a compact servo system while ensuring a certain degree of motor controllability.

Here, in the above servo system, the motor includes a first detection unit that detects an abnormality regarding wireless communication between the first communication unit and the second communication unit, and an abnormality detected by the first detection unit. The motor may further include an abnormality processing unit that issues a stop command to the current control unit to stop the drive current and stops the motor when the motor is stopped. Examples of abnormalities related to wireless communication include communication conditions that can adversely affect proper servo control of the motor, such as interruption of wireless communication for a predetermined time or more and increase in noise. Since a current control unit is disposed on the motor side, if an abnormality in wireless communication is detected by the first detection unit, a stop command is issued to the current control unit to stop the drive current. By issuing , the motor can be stopped immediately without being affected by the abnormality. With such a configuration, even if a problem should occur in the wireless communication contributing to the compact servo system, the safety of the servo system can be suitably maintained.

Here, in the above servo system, the abnormality processing unit is configured to detect an abnormality based on the drive history of the motor, if the abnormality is within a predetermined range even when the first detection unit detects the abnormality. A drive command may be issued to the current control unit to continue driving the motor. The term "within a predetermined range" refers to the degree of abnormality in wireless communication that can be handled by controlling the motor only by the current control section. For example, a case can be considered in which the disconnection time of wireless communication between the control device and the motor is extremely short. In the case of such a mild wireless communication abnormality, it may be possible to estimate how the motor should be driven based on the past drive history of the motor. In such a case, the abnormality processing unit may continue the operation of the motor instead of stopping the motor due to the abnormality in wireless communication. However, if the abnormality subsequently deviates from a predetermined range, the abnormality processing unit preferably stops the motor as described above.

In the servo system described above, the second communication unit of the motor is further configured to send and receive signals via wireless communication with an emergency stop device that stops the drive of the motor in an emergency. The first detection section of the motor may be further configured to detect an abnormality regarding wireless communication between the emergency stop device and the second communication section. The abnormality processing unit controls the current control unit to control the drive current when the first detection unit detects the abnormality, even if the emergency stop device does not output a signal for emergency stop. The motor may be stopped by issuing a stop command to stop the motor. In this way, even if an abnormality occurs not only in the wireless communication between the control device and the motor, but also in the wireless communication between the emergency stop device and the motor, the current control installed on the motor side will be affected. By issuing a stop command to the motor, the motor can be stopped immediately without being affected by abnormalities in wireless communication, thereby increasing the safety of the servo system.

Here, the above servo system may further include another motor. Each of the motor and the other motor includes the second communication section, the drive circuit, and the current control section, and further includes an inter-motor communication section that exchanges signals with each other via wireless communication. the first communication unit of the control device is configured to send and receive signals to and from the motor and the other motor via wireless communication; Control loop calculations regarding position and speed are performed based on command values for the motor and the other motor, and the first signal which is a feedback signal related to the operation of the motor and the other motor, and the calculation results are , the output may be configured to be output to each of the motor side and the other motor side via the first communication unit. Even when a control device controls multiple motors in this way, the environment for motor servo control can be improved by separating the positions of the position/speed control section and current control section into the control device side and the motor side. It becomes possible to construct a servo system compactly while maintaining a suitable value.

In the servo system configured in this manner, the motor and the other motor may be synchronously controlled by the control device. The motor includes a first detection unit that detects an abnormality regarding wireless communication between the first communication unit and the second communication unit, and when the first detection unit detects an abnormality, the motor A stop command to stop the drive current is issued to the current control unit, and a stop command to stop the drive current is issued to the current control unit of the other motor via the inter-motor communication unit, and the motor and an abnormality processing unit that stops the other motors in synchronization. According to such a configuration, when an abnormality regarding wireless communication between the motor and the control device occurs when synchronous control is performed between the motor and other motors, the current control section of each motor is On the other hand, by issuing a stop command, it is possible to suitably stop both while maintaining mutual synchronous control, and it is possible to suppress the adverse effects caused by the stop.

Furthermore, in the above servo system, each of the motor and the other motor may further include a wireless power supply unit that sends and receives signals for wireless power supply to each motor. The motor further includes a second detection unit that detects an abnormality regarding communication for wireless power supply by the wireless power supply unit, and the abnormality processing unit is configured to detect an abnormality when the second detection unit detects an abnormality. , issues a stop command to the current control section of the motor to stop the drive current, and also issues a stop command to the current control section of the other motor to stop the drive current via the inter-motor communication section. and stop this motor and the other motors synchronously. The wireless power supply unit can, for example, wirelessly supply power from the outside to an electrical device related to a motor. For example, wireless power supply is performed to supply driving power to an encoder, a sensor provided in a motor for servo control, and the like.

Even in the case of wireless power supply, if an abnormality occurs in the wireless communication, it becomes impossible to transmit the necessary power to the motor, and there is a possibility that suitable servo control may be hindered. In particular, when a motor and another motor are controlled synchronously with each other, driving one motor will greatly affect the other motor. Therefore, by using the inter-motor communication section between motors, even if an abnormality is detected regarding communication for wireless power supply, each By issuing a stop command to the current control section of the motor, it is possible to suitably stop both while maintaining mutual synchronous control.

Alternatively, in the above servo system, the motor may include a first detection section that detects an abnormality regarding wireless communication between the first communication section and the second communication section, and a first detection section. When an abnormality is detected, a command to stop the drive current issued from the control device is received from the other motor via the inter-motor communication unit, and the current of the motor is adjusted according to the received stop command. The motor may further include an abnormality processing section that causes the control section to stop the motor. According to this configuration, when an abnormality regarding wireless communication occurs, a stop command from the control device is delivered to the motor via a path where no abnormality has occurred, that is, via another motor. A stop command can be issued to the current control section to stop the motor.

Here, the present disclosure can be viewed from the aspect of a motor incorporated in a servo system. That is, the present disclosure provides a control device having a position/speed control section that performs control loop calculations regarding position and speed based on a command value to a motor and a first signal that is a feedback signal related to the operation of the motor. , a communication unit configured to send and receive signals via wireless communication, a drive circuit that generates a drive current for the motor, and the position/speed control received via wireless communication via the communication unit. a current control unit that performs a control loop calculation regarding the drive current based on the calculation result by the unit and a second signal that is a feedback signal related to the drive current of the motor in the drive circuit, and outputs the result to the drive circuit; It is equipped with a motor. Note that the technical ideas disclosed for the servo system described above can also be applied to the motor disclosed in the present application, as long as no technical discrepancy occurs.

Furthermore, the motor includes a first detection section that detects an abnormality regarding wireless communication with the control device, and a function that causes the current control section to stop the drive current when the first detection section detects the abnormality. The motor may also include an abnormality processing unit that issues a stop command to stop the motor. With this configuration, when an abnormality occurs in wireless communication, the abnormality processing section can stop the motor regardless of the abnormality.

The servo system can be constructed compactly while maintaining a suitable environment for motor servo control.

FIG. 1 is a diagram showing a schematic configuration of a servo system. 2 is a diagram showing a control structure for servo control included in the servo system shown in FIG. 1. FIG. 2 is a first flowchart showing a process flow when an abnormality occurs in wireless communication in the servo system disclosed in the present application. 12 is a second flowchart showing the flow of processing when an abnormality occurs in wireless communication in the servo system disclosed in the present application. FIG. 7 is a third flowchart showing the flow of processing when an abnormality occurs in wireless communication in the servo system disclosed in the present application. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, the same reference numerals are attached to the same or corresponding parts in the figures, and the description thereof will not be repeated. In the present disclosure, as one exemplary form of the servo system, a form in which the number of motors servo-controlled by a control device (PLC) is two is shown, but the number of motors servo-controlled may be one, or three. It doesn't matter if it's more than one.

FIG. 1 is a diagram showing a schematic configuration of a servo system. The objects of servo control by the servo system are two motors 2 and motor 2a. Further, FIG. 2 shows a servo control structure formed in the servo system. The servo system in FIG. 1 includes a PLC (Programmable Logic Controller) 5 that is a control device, two motors 2 and 2a, and an emergency stop device 8. The servo system is a system for servo-controlling the motors 2 and 2a of each control axis, which are the control targets, to follow the operation command signal pcmd generated by the PLC 5. In the present disclosure, reference will be made to a case in which the motor 2 and the motor 2a are servo-controlled independently, and a case in which the motor 2 and the motor 2a are servo-controlled in synchronization (synchronous control). Which case is adopted depends on the purpose of driving the device etc. driven by the motors 2 and 2a.

Examples of devices in which the motors 2 and 2a are incorporated include, for example, an XY table of a machine tool or a transport device, an arm of an industrial robot having a plurality of joint axes, and the like. Motors 2 and 2a are AC servo motors. Encoders 28 and 28a are attached to the motors 2 and 2a, respectively, and signals regarding the operation of each motor are transmitted as feedback by the encoders. This feedback transmitted signal (hereinafter referred to as a feedback signal) includes, for example, position information about the rotational position (angle) of the rotational shaft of the motors 2, 2a, information about the rotational speed of the rotational shaft, and the like.

Further, the PLC 5 generates an operation command signal regarding the operation (motion) of the motors 2 and 2a. Here, in the present disclosure, regarding a control structure (servo control structure) for servo control of the motors 2 and 2a, a position/speed control unit 52 that performs control loop calculations regarding position and speed is arranged on the PLC 5 side, and each motor Current control units 22 and 22a that perform control loop calculations regarding the drive current are arranged in each of the motors 2 and 2a. That is, in the present disclosure, the servo control structure is not arranged in one device, but is divided into the PLC 5, which is a control device, and each motor. The PLC 5 and each motor are configured to exchange information with each other via wireless communication. Details of the servo control structure will be described later.

Furthermore, each of the motors 2 and 2a is provided with a drive circuit 23 and 23a that generates a drive current for each motor in accordance with a current command that is a calculation result by the current control section 22 and 22a. The drive circuits 23 and 23a are so-called inverter devices. AC power sent from an AC power source (not shown) is used to power the drive circuits 23, 23a. In the present disclosure, the drive circuits 23 and 23a are of a type that receives three-phase alternating current, but may be of a type that receives single-phase alternating current.

Here, based on FIG. 2, a servo control structure formed over the PLC 5 and each motor of the servo system disclosed in the present application will be described. In this servo system, a servo control structure corresponding to each control axis is formed. That is, the servo control structure corresponding to the motor 2 is formed over both the motor 2 and the PLC 5, and the servo control structure corresponding to the motor 2a is formed over both the motor 2a and the PLC 5. Since each servo control structure has substantially the same content, the detailed explanation will be centered on the servo control structure corresponding to the motor 2. Moreover, as will be described later, the transmission and reception of signals between the PLC 5 and each of the motors 2 and 2a is performed via wireless communication. In FIG. 2, wireless communication and wired communication are not shown separately. Transmission from 28 to PLC 5 is performed via wireless communication.

The servo control structure corresponding to the motor 2 includes a position control section 521 and a speed control section 522 on the PLC 5 side, and a current control section 22 on the motor 2 side. The position control section 521 and the speed control section 522 correspond to the portion of the position/speed control section 52 shown in FIG. 1 that corresponds to the motor 2. Therefore, the position/speed control section 52 includes a position control section 521, a speed control section 522, a position control section 521a, and a speed control section 522a, which correspond to the motors 2 and 2a. The position control unit 521 performs, for example, proportional control (P control). Specifically, the speed command vcmd is calculated by multiplying the position deviation, which is the deviation between the position command pcmd generated within the PLC 5 and the detected position, by a predetermined position proportional gain.

The speed control unit 522 performs, for example, proportional integral control (PI control). Specifically, the integral amount of speed deviation, which is the deviation between the speed command vcmd calculated by the position control unit 521 and the detected speed, is multiplied by a predetermined speed integral gain, and the sum of the calculation result and the speed deviation is multiplied by a predetermined value. The torque command τcmd is calculated by multiplying by the speed proportional gain. Further, the speed control unit 522 may perform P control instead of PI control. The calculated torque command τcmd is the calculation result of the position/speed control section 52, and the calculation result is transmitted to the motor 2 side via wireless communication.

The current control unit 22 issues a current command Ccmd to the drive circuit 23 based on the deviation between the torque command τcmd calculated by the speed control unit 522 and the drive current supplied from the drive circuit 23 to the windings of the motor 2. A driving current for the motor 2 is generated thereby. The current control unit 22 includes a filter related to the torque command (first-order low-pass filter) and one or more notch filters, and may have a cutoff frequency or the like related to the performance of these filters as a control parameter.

In the servo control structure, the detected position signal and the detected speed signal calculated based on the detection signal of the encoder 28 of the motor 2 are sent to the position control section 521 and the speed control section 522 as feedback signals regarding the position and speed, respectively. feedback is given. This feedback signal is also transmitted to the PLC 5 via wireless communication.

Further, as described above, regarding the servo control structure corresponding to the motor 2a, the position control section 521a and the speed control section 522a are arranged on the PLC 5 side, and the current control section 22a is arranged on the motor 2a side. The position control section 521a, the speed control section 522a, and the current control section 22a are functional sections corresponding to the position control section 521, the speed control section 522, and the current control section 22, respectively.

Next, other functional units included in the PLC 5, motors 2 and 2a, and emergency stop device 8 included in the servo system will be explained. First, the functional units included in the PLC 5 will be explained. The PLC 5 includes a communication section 51 and a position/speed control section 52. The latter has already been mentioned. The former communication unit 51 is a functional unit that performs wireless communication with each of the motors 2 and 2a that are subject to servo control by the PCL 5. Therefore, corresponding communication units 21 and 21a are also provided for the motors 2 and 2a that are communication partners, respectively. Any type of wireless communication can be used for wireless communication between the communication unit 51 and the communication unit 21, and between the communication unit 51 and the communication unit 21a. Between the communication unit 51 and the communication unit 21, a detected speed signal and a detected position signal based on the torque command τcmd from the speed control unit 522 to the motor 2 side shown in FIG. will be sent via. The same is substantially the same between the communication section 51a and the communication section 21a.

Next, the motor 2 includes a communication section 21 , a current control section 22 , a drive circuit 23 , a detection section 24 , an abnormality processing section 25 , an inter-motor communication section 26 , a wireless power supply section 27 , and an encoder 28 . Since the communication section 21, current control section 22, drive circuit 23, and encoder 28 have already been mentioned, the other functional sections will mainly be explained. Note that the communication unit 21 can perform wireless communication with the emergency stop device 8 in addition to the PLC 5. Therefore, a communication section 81 corresponding to the emergency stop device 8 serving as a communication partner is also provided.

The detection unit 24 is a functional unit that detects an abnormality regarding wireless communication when the motor 2 performs wireless communication with a nearby communication partner. In the present disclosure, the motor 2 performs wireless communication with the PLC 5 and the emergency stop device 8. Further, the motor 2 is supplied with drive power from a supply device 50 to the encoder 28 and other sensors (not shown) mounted on the motor 2 through wireless communication by a wireless power supply unit 27 (described later). Wireless power supply is also subject to abnormality detection by the detection unit 24. Therefore, the detection unit 24 corresponds to the first detection unit and the second detection unit disclosed in the present application. Abnormality detection by the detection unit 41 is performed based on various parameters of the signal to be wirelessly communicated. For example, an abnormality can be detected using the length of time during which the signal is interrupted, the magnitude of noise in the signal (SN ratio), and the like. Note that, as will be described later, the motor 2 can send and receive signals to and from the motor 2a via wireless communication using the inter-motor communication unit 26. This wireless communication between motors may also be subject to abnormality detection by the detection unit 24.

The abnormality processing unit 25 is a functional unit that issues a predetermined command to the current control unit 22 to control the drive of the motor 2 when the detection unit 24 detects an abnormality in wireless communication. If an abnormality occurs in the wireless communication, there is a possibility that the safety of driving the motor 2 may be impaired due to the abnormality. Therefore, from the viewpoint of safety regarding the drive of the motor 2, the abnormality processing unit 25 safely controls the drive of the motor 2 by issuing a command regarding current control to the current control unit 22. In the present disclosure, among the functional units related to servo control of the motor 2, the current control unit 22 is arranged on the motor 2 side, so even if an abnormality occurs in the wireless communication between the PLC 5 and the motor 2, Even if there is, it is possible to control the drive of the motor 2 to some extent via the current control section 22. Note that the predetermined command issued to the current control unit 22 by the abnormality processing unit 25 may be any command that can safely control the motor 2, such as stopping the motor 2 or driving the motor 2 within a safe range. Examples include instructions to continue.

The inter-motor communication section 26 is a functional section for performing wireless communication with the motor 2a. Therefore, an inter-motor communication section 26a corresponding to the motor 2a is also provided. Next, the wireless power supply unit 27 supplies drive power for driving the encoder 28 and other sensors (not shown) mounted on the motor 2, etc., which is output via wireless communication from a supply device 50 provided externally. This is a functional unit that receives the signal and converts the electrical energy of the received signal into DC power for driving the encoder 28 and the like. A known technique can be adopted as a wireless power feeding method between the wireless power feeding unit 27 and the supply device 50, and examples thereof include an electromagnetic induction method and a magnetic resonance method.

Similarly to the motor 2, the motor 2a also includes a communication section 21a, a current control section 22a, a drive circuit 23a, a detection section 24a, an abnormality processing section 25a, an inter-motor communication section 26a, a wireless power supply section 27a, and an encoder 28a. It has a functional part. Note that it is the supply device 50a that supplies power to the wireless power supply unit 27a via wireless communication.

Next, the emergency stop device 8 has a communication section 81 and a stop control section 82. The communication section 81 is as already described. The stop control unit 82 is a functional unit that outputs an emergency stop signal to the motor 2 that is the other party of wireless communication. The emergency stop signal is output when the user presses a switch (not shown) provided on the emergency stop device 8. The output emergency stop signal is transmitted to the motor 2 side via the communication unit 81, and activates a cutoff device (not shown) provided in the motor 2 to cut off the path of the drive current supplied from the drive circuit 23. By doing so, the motor 2 is brought to an emergency stop. In this way, the emergency stop device 8 is an important device for the safety of the motor 2, so in order to ensure that the emergency stop signal is delivered to the motor 2 in an emergency, the communication section 81 of the emergency stop device 8 and the motor 2 are always connected. Wireless communication with the communication unit 21 needs to be established. Therefore, a reference signal for confirming the establishment of this wireless communication is transmitted from the stop control section 82 to the motor 2 side, and a response signal in response thereto is transmitted from the motor 2 to the emergency stop device 8 side. By monitoring the exchange of this reference signal and response signal, it can be determined whether wireless communication between the two is secured. If the communication is interrupted, the situation will be detected by the detection unit 24 on the motor 2 side.

<Safety control 1>
Here, the first safety control executed in the motor 2 will be explained based on FIG. 3. The safety control is repeatedly executed in cooperation with each functional section of the motor 2 shown in FIG. Note that in the safety control, the motor 2 and the motor 2a are not synchronously controlled. Therefore, the safety control is executed by the motor 2 alone.

First, in S101, it is determined whether an abnormality has occurred in the wireless communication between the communication section 51 of the PLC 5 and the communication section 21 of the motor 2. This determination is made by the detection unit 24. For example, if the communication unit 21 is unable to receive the calculation result (i.e. torque command τcmd) of the position/speed control unit 52 (position control unit 521 and speed control unit 522) of the PLC 5 for a predetermined period or longer, , it is possible to detect that an abnormality has occurred. Alternatively, the occurrence of an abnormality can also be detected when the noise ratio in the signal of the calculation result detected by the communication unit 21 is higher than a predetermined threshold. Regarding the determination of communication abnormality detection, consider the location where the servo system shown in Figure 1 is installed and the presence of obstacles (including fixed and movable ones) between the PLC 5 and the motor 2. It may be done as appropriate. If an affirmative determination is made in S101, it is determined in S102 that an abnormality has been detected in wireless communication. Further, if a negative determination is made in S101, the process advances to S106.

After the abnormality is detected in S102, it is determined in S103 whether or not the detected abnormality is small. The small degree here means that although an abnormality has occurred in wireless communication, the degree of abnormality is such that it is assumed that the current control unit 22 of the motor 2 can maintain the driving state of the motor 2 relatively safely. This is a mild case. As described in S105 below, the abnormality processing unit 25 tries to continue driving the motor 2 by using the current control unit 22 when the degree of abnormality is small. Therefore, the determination as to whether or not the abnormality is of a small degree is made in consideration of whether or not the process of S105 can be performed. For example, if the period during which wireless communication is not possible is shorter than 1.5 times the predetermined period used in the determination in S101, the abnormality processing unit 25 in S105 drives the motor 2. It can be judged that continuation is possible. In such a case, the "period shorter than 1.5 times the predetermined period" can be used as the threshold for determining the degree of smallness in S103. If a negative determination is made in S103, the process proceeds to S104, and if an affirmative determination is made, the process proceeds to S105.

In S104, the abnormality processing unit 25 outputs a command to stop the drive current, that is, a stop command, to the current control unit 22 in order to stop the motor 2. If there is an abnormality in wireless communication, the motor 2 is not under servo control by the PLC 5, but the current control unit 22 remaining on the motor 2 side is can be used to stop the motor 2 while keeping it under some degree of control. This configuration is extremely useful from the viewpoint of safety of the motor 2, and suitably reinforces wireless communication between the PLC 5 and the motor 2 in the servo system. After S104 ends, the safety control is repeated again.

Further, in S105, the abnormality processing section 25 uses the current control section 22 to control the motor 2.
Processing to continue driving is performed. If the abnormality in wireless communication is small, the operation of the motor 2 is controlled to some extent using current control by the current control unit 22, although the motor 2 is not under servo control by the PLC 5. Therefore, it is possible to safely avoid adverse effects caused by small-scale abnormalities. Specifically, the abnormality processing unit 25 uses information regarding the past drive history of the motor 2 to output a command to the current control unit 22 to continue driving the motor 2. For example, in situations where the rotational speed of motor 2 has little change or is constant, the required drive current is relatively small, so the drive torque corresponding to the rotational speed at the time of abnormality is calculated from the drive history information. Then, a command corresponding to the drive torque is output to the current control section 22. Thereby, even if there is an abnormality in the wireless communication with the PLC 5, the driving of the motor 2 can be controlled with the motor 2 under a certain degree of control, and the frequency of stopping the motor 2 can be reduced. After S105 ends, the safety control is repeated again.

Here, if a negative determination is made in S101, the process advances to S106. In S106, it is determined whether an abnormality has occurred in the wireless communication between the communication section 81 of the emergency stop device 8 and the communication section 21 of the motor 2. This determination is made by the detection unit 24. As described above, reference signals and response signals are exchanged between the emergency stop device 8 and the motor 2. When the detection unit 24 detects that this signal exchange is interrupted, it can detect that an abnormality has occurred in the wireless communication between the two. If an affirmative determination is made in S106, it is determined in S107 that an abnormality has been detected in wireless communication. Moreover, if a negative determination is made in S106, the safety control is repeated again.

The emergency stop device 8 is a highly important device for the safety of the motor 2. Therefore, if an abnormality occurs in the wireless communication with the emergency stop device 8, it is preferable to stop the motor 2 immediately from the viewpoint of ensuring safety. Therefore, after it is determined in S107 that an abnormality has been detected, the process proceeds to S104, and the motor 2 is stopped by outputting a stop command to the current control section 22 as described above.

According to the safety control shown in FIG. 3, the position/speed control section 52 and the current control section 22 are arranged in the PLC 5 and the motor 2, respectively, and information can be exchanged between the two by wireless communication. In the configured servo system, even if an abnormality occurs in the wireless communication, the operation of the motor 2 can be controlled with the motor 2 under some degree of control. As a result, it becomes possible to make the servo system more compact and drive the motor safely.

<Safety control 2>
Here, the second safety control executed in the motor 2 will be explained based on FIG. 4. In addition, in the safety control, the motor 2 and the motor 2a are synchronously controlled, and during the control, the safety control is repeatedly executed by the cooperation of each functional unit of both motors.

In S201, it is determined whether an abnormality has occurred in the wireless communication between the communication unit 51 of the PLC 5 and the communication unit 21 of the motor 2. The process in S201 is substantially the same as the process in S101. If an affirmative determination is made in 201, the process proceeds to S202, and in S202 it is determined that an abnormality has been detected in wireless communication. Further, if a negative determination is made in S201, the process advances to S205.

After the abnormality is detected in S202, in S203, the abnormality processing unit 25 issues a command to the current control unit 22 of the motor 2 to stop the drive current in order to stop the motor 2 and the motor 2a synchronously; That is, at the same time as outputting the stop command, the stop command is also output to the current control section 22a of the motor 2a that is subject to synchronous control. A stop command to the current control section 22a is delivered via the inter-motor communication sections 26 and 26a. Inter-motor communication section 26, 26a
By using this, the stop command can be reliably delivered to the motor 2a without being adversely affected by a wireless communication abnormality between the PLC 5 and the motor 2. As a result of the process in S203, both motors can be stopped while being synchronized by the current control section 22 in the motor 2 and by the current control section 22a in the motor 2a (the process in S204). After S204 ends, the safety control is repeated again.

Here, if a negative determination is made in S201, the process advances to S205. In S205, it is determined whether an abnormality has occurred regarding wireless communication for wireless power supply between the supply device 50 and the wireless power supply unit 27 of the motor 2. This determination is made by the detection unit 24. As mentioned above, driving power for the encoder 28 and the like is wirelessly supplied between the supply device 50 and the wireless power supply section 27, and if the wireless power supply is no longer performed, it will be difficult to drive the motor 2, so such a method is necessary. In this case, it is preferable to stop the motor 2. Therefore, for example, if the power per unit time sent from the supply device 50 via the wireless power supply unit 27 is less than a predetermined threshold, it is detected that an abnormality has occurred regarding wireless communication for wireless power supply. can. If an affirmative determination is made in S205, it is determined in S202 that an abnormality has been detected in wireless communication. Moreover, if a negative determination is made in S205, the safety control is repeated again.

According to the safety control shown in FIG. 4, the position/speed control section 52 and the current control sections 22, 22a are arranged in the PLC 5 and the motors 2, 2a, respectively, and information is exchanged between the two by wireless communication. In a servo system configured to be able to perform this, even if an abnormality occurs in the wireless communication, it is possible to safely stop motor 2 and motor 2a, which are under synchronous control, under a certain degree of control. can. As a result, it becomes possible to make the servo system more compact and drive the motor safely.

<Safety control 3>
Here, the third safety control executed in the motor 2 will be explained based on FIG. 5. In the safety control, the motor 2 and the motor 2a are not synchronously controlled, but the respective functional units of both motors cooperate to repeatedly execute the safety control.

In S301, it is determined whether an abnormality has occurred in the wireless communication between the communication unit 51 of the PLC 5 and the communication unit 21 of the motor 2. The process in S301 is substantially the same as the process in S101. When an affirmative determination is made in step 301, the process proceeds to step S302, and in step S302, it is determined that an abnormality has been detected in the wireless communication. Moreover, if a negative determination is made in S301, the safety control is repeated again.

After the abnormality is detected in S302, in S303, a stop command for stopping the motor 2 generated by the PLC 5 is received via the motor 2a with which wireless communication with the PLC 5 is normal. Specifically, the motor 2a receives a stop command addressed to the motor 2 from the PLC 5, and the motor 2 further receives the stop command via the inter-motor communication units 26 and 26a. Then, in S304, the abnormality processing unit 25 passes the received stop command to the current control unit 22 to stop the motor 2. As a result, even if an abnormality occurs regarding wireless communication between the PLC 5 and the motor 2, the motor 2 can be safely stopped. After S304 ends, the safety control is repeated again.

According to the safety control shown in FIG. 5, the position/speed control section 52 and the current control section 22 are arranged in the PLC 5 and the motor 2, respectively, and information can be exchanged between the two by wireless communication. In the configured servo system, even if an abnormality occurs in the wireless communication, the operation of the motor 2 can be controlled with the motor 2 under some degree of control. As a result, it becomes possible to make the servo system more compact and drive the motor safely.

<Additional note 1>
A servo system including a control device (5) and a motor (2),
The control device (5) includes:
a first communication unit (51) configured to exchange signals with the motor (2) via wireless communication;
A control loop calculation regarding position and speed is performed based on a command value to the motor (2) and a first signal which is a feedback signal related to the operation of the motor (2), and the calculation result is applied to the first signal. a position/speed control unit (52) that outputs to the motor side via a communication unit;
has
The motor (2) is
a second communication unit (21) configured to exchange signals with the control device (5) via wireless communication;
a drive circuit (23) that generates a drive current for the motor (2);
the calculation result output by the position/speed control section (52) and received by the second communication section (21), and a feedback signal related to the drive current of the motor (2) in the drive circuit (23); a current control unit (22) that performs a control loop calculation regarding the drive current based on the second signal and outputs the calculation result to the drive circuit;
A servo system with

<Additional note 2>
A control device having a position/speed control unit (52) that performs control loop calculations regarding position and speed based on a command value to the motor (2) and a first signal that is a feedback signal related to the operation of the motor. 5), a communication unit (21) configured to send and receive signals via wireless communication,
a drive circuit (23) that generates a drive current for the motor (2);
A feedback signal, which is a feedback signal related to the calculation result by the position/speed control unit and the drive current of the motor (2) in the drive circuit (23), received by wireless communication via the communication unit (21). a current control unit (22) that performs a control loop calculation regarding the drive current based on the two signals and outputs it to the drive circuit;
A motor.

2, 2a Motor 5 PLC
21, 21a Communication section 22, 22a Current control section 23, 23a Drive circuit 24, 24a Detection section 25, 25a Abnormality processing section 26, 26a Inter-motor communication section 27, 27a Wireless power supply section 28, 28a Encoder 50 Supply device 51 Communication Section 52 Position/speed control section

Claims (10)

A servo system including a control device and a motor,
The control device includes:
a first communication unit configured to exchange signals with the motor via wireless communication;
A control loop calculation regarding position and speed is performed based on a command value to the motor and a first signal that is a feedback signal related to the operation of the motor, and the calculation result is transmitted to the motor via the first communication unit. A position/speed control section that outputs to the motor side,
has
The motor is
a second communication unit configured to exchange signals with the control device via wireless communication;
a drive circuit that generates a drive current for the motor;
related to the drive current based on the calculation result output by the position/speed control unit and received by the second communication unit, and a second signal that is a feedback signal related to the drive current of the motor in the drive circuit. a current control unit that performs a control loop calculation and outputs the calculation result to the drive circuit;
A servo system with The motor is
a first detection unit that detects an abnormality regarding wireless communication between the first communication unit and the second communication unit;
an abnormality processing unit that issues a stop command to the current control unit to stop the drive current and stops the motor when an abnormality is detected by the first detection unit;
The servo system according to claim 1, further comprising:. The abnormality processing unit is configured to issue a drive command to the current control unit based on the drive history of the motor, if the abnormality is within a predetermined range even when the first detection unit detects the abnormality. and continue driving the motor.
The servo system according to claim 2. The second communication unit of the motor is further configured to send and receive signals via wireless communication with an emergency stop device that stops the drive of the motor in an emergency;
The first detection unit of the motor is further configured to detect an abnormality regarding wireless communication between the emergency stop device and the second communication unit,
The abnormality processing unit is configured to stop the drive current to the current control unit when the first detection unit detects an abnormality, even if the emergency stop device does not output a signal for emergency stop. issuing a stop command to stop the motor;
The servo system according to claim 2 or claim 3. The servo system further includes another motor,
Each of the motor and the other motor includes the second communication section, the drive circuit, and the current control section, and further includes an inter-motor communication section that exchanges signals with each other via wireless communication. ,
The first communication unit of the control device is configured to send and receive signals to and from the motor and the other motor via wireless communication,
The position/speed control unit of the control device controls the position based on command values for the motor and the other motor, and the first signal that is a feedback signal related to the operation of the motor and the other motor. and is configured to perform control loop calculations regarding speed and output the calculation results to each of the motor side and the other motor side via the first communication unit.
The servo system according to claim 1. The motor and the other motor are synchronously controlled by the control device,
The motor is
a first detection unit that detects an abnormality regarding wireless communication between the first communication unit and the second communication unit;
When the first detection section detects an abnormality, it issues a stop command to the current control section of the motor to stop the drive current, and also controls the current control of the other motor via the inter-motor communication section. an abnormality processing unit that issues a stop command to stop the drive current to the motor and stops the motor and the other motors in synchronization;
The servo system according to claim 5, further comprising:. Each of the motor and the other motor further includes a wireless power supply unit that sends and receives signals for wireless power supply to each of the motors,
The motor is
further comprising a second detection unit that detects an abnormality regarding communication for wireless power supply by the wireless power supply unit,
The abnormality processing unit issues a stop command to the current control unit of the motor to stop the drive current when an abnormality is detected by the second detection unit, and also issues a stop command to the current control unit of the motor to stop the drive current, and also outputs a stop command to the current control unit of the motor to stop the drive current. issuing a stop command to stop the drive current to the current control unit of the other motor, and synchronously stopping the motor and the other motor;
The servo system according to claim 6. The motor is
a first detection unit that detects an abnormality regarding wireless communication between the first communication unit and the second communication unit;
When an abnormality is detected by the first detection unit, a drive current stop command issued from the control device is received from the other motor via the inter-motor communication unit, and the received stop command is an abnormality processing unit that causes the current control unit of the motor to stop the motor according to the above;
The servo system according to claim 5, further comprising:. a control device having a position/speed control section that performs control loop calculations regarding position and speed based on a command value to the motor and a first signal that is a feedback signal related to the operation of the motor; a communication unit configured to send and receive signals;
a drive circuit that generates a drive current for the motor;
related to the drive current based on the calculation result by the position/speed control unit and a second signal that is a feedback signal related to the drive current of the motor in the drive circuit, which is received by wireless communication via the communication unit. a current control unit that performs control loop calculation and outputs it to the drive circuit;
A motor. a first detection unit that detects an abnormality regarding wireless communication with the control device;
an abnormality processing unit that issues a stop command to the current control unit to stop the drive current and stops the motor when an abnormality is detected by the first detection unit;
The motor according to claim 9, further comprising:.

Images