JP7225946B2 - robot system, robot controller - Google Patents

Description

The present invention relates to a robot system and a robot controller.

As a form of use of robots, tracking is known in which a work is performed while following changes in the position of a work conveyed by a conveying device. At this time, it has been proposed to improve the accuracy of tracking by also controlling the conveying device by the control device of the robot (see, for example, Patent Document 1). Hereinafter, a mode in which tracking is performed while controlling the drive shafts of the robot other than the joints of the robot, for example, the drive shafts of the transfer device, by the controller of the robot will be referred to as additional axis tracking.

JP-A-10-105217

In additional axis tracking, one master robot controller controls the transport device, and one or more slave robot controllers operate based on command values sent from the master robot controller. In some cases, a robot system is constructed in which a device is provided and a plurality of robots perform work.

At this time, the master-side control device notifies the slave-side control device of the initial position of the workpiece to be transferred by the transfer device, and then controls the robot itself while generating a command value to be given to the transfer device. It is sent to the control device on the side each time. To put it simply, the command value given to the conveying device is a value indicating the target position of the conveying device. If this command value is known, the target position of the conveying device, that is, the position to which the workpiece is to be conveyed can be estimated. It becomes possible.

The slave-side controller estimates the position of the work based on the most recently received command value, and performs tracking by operating the slave-side robot to follow the movement of the work.

However, the control device on the master side controls not only the transfer device but also the robot as described above. Although the master-side control device needs to transmit command values to all connected slave-side control devices, the number of connected slave-side control devices is not necessarily one. Therefore, if the load required for communication increases, there is a risk that the control device on the master side will interfere with the control of the robot.

Also, if the control device on the slave side performs control in a state in which communication has not been performed correctly, the latest command value has not been received, so there is a risk that the followability of tracking will deteriorate. On the other hand, if it is configured to check whether or not it has been received and to resend a new command value, the load on not only the slave side control device but also the master side control device will increase. .

Therefore, while reducing the load on the master-side control device and the load on the slave-side control device, the slave-side control device alone determines whether or not communication has been performed correctly, and the communication is performed correctly. To provide a robot system and a robot control device capable of coping with a case where there is no robot.

In the first aspect of the invention, the robot system performs additional axis tracking for collectively controlling the movement of the transfer device and the robot. A master-side robot controlled by a controller, one or more slave-side controllers communicably connected to the master-side controller, and one or more slave-side controllers controlled by the slave-side controllers. and a robot on the slave side.

The control device on the master side includes a command value generation unit that generates a command value to be given to the transport device, a speed information generation unit that generates speed information capable of specifying the speed of the transport device, and the generated command value and speed information. as control information to the control device on the slave side by UDP communication.

UDP communication that communicates using UDP (User Datagram Protocol) is so-called connectionless communication, and although the reliability of the data itself is not guaranteed, TCP (Transmission Control Protocol) is used to ensure the reliability of the data itself. The load required for communication is greatly reduced compared to TCP communication in which communication is performed using

Therefore, one-to-many communication becomes possible while reducing the communication load at the time of tracking by performing UDP communication for the control information that needs to be repeatedly transmitted to the control device on the slave side.
However, since UDP communication does not guarantee data reliability, it is difficult to directly use it for robot control. In addition, in UDP communication, since the transport layer does not guarantee or confirm that the communication was performed correctly, if the most recent UDP communication was performed correctly, the command value received at that time will be the latest. While stored as a command value, even when UDP communication is not performed correctly and a new command value is not received, the past command value already received is treated as the latest command value as it is.

In other words, if the UDP communication is not performed correctly, the latest command value is not updated, and if the UDP communication is not performed correctly, the control device on the slave side will not be able to perform the previous control. The same command value is used to control the robot on the slave side. If the UDP communication is performed correctly after that, the latest command value will be updated, so the control device on the slave side will perform control based on the correct latest command value.

However, since the command value transmitted from the control device on the master side is a value indicating the target position of the transport device as described above, the fact that the command value is the same as the previous time means that the target position of the transport device is the same as the previous time. This means the same state as , that is, the state in which the conveying device is stopped.

In this case, the slave-side control device determines that the transfer device is stopped, and performs control to decelerate or stop the robot. After that, when the UDP communication is correctly performed and the latest command value is updated, the slave-side control device operates the decelerated or stopped robot at high speed in order to move it to the updated target position. It will be.

Thus, when UDP communication is adopted to reduce the communication load, there is a risk that the speed of the slave-side robot will change discontinuously. At this time, inquiring the master side control device about the success or failure of UDP communication or requesting retransmission results in an increase in the load on the master side control device and the slave side control device. This goes against the gist of adopting UDP communication in order to reduce

Therefore, the slave-side control device includes a communication unit that receives control information transmitted from the master-side control device, a storage unit that stores control information used in the previous control, and a master-side control device. and a determination unit that determines whether UDP communication between the controller and the master side control device was not performed correctly. and a correction unit for correcting the value.

Then, the determining unit determines that the command value used in the current control matches the command value used in the previous control, and the speed of the conveying device used in the current control exceeds a predetermined reference value. If so, it is determined that the UDP communication with the control device on the master side has not been performed correctly.

The command value for the transport device is data indicating the target position of the transport device as described above. Therefore, a state in which the command value used in the current control matches the previous command value stored in the storage unit means that the target position is the same as the previous state, that is, the conveying device is stopped. . However, even if the current command value and the previous command value match, the transportation device may actually be stopped due to an emergency stop, etc., and it cannot be determined that the UDP communication was not performed correctly based on this alone. .

Therefore, the determining unit uses the speed of the conveying device to determine whether the UDP communication was not performed correctly. This is because it is difficult to imagine that the speed of the transport device suddenly becomes zero in a control cycle of several milliseconds. This is because if the reference value is exceeded, it can be determined that the command value has not been updated, that is, the UDP communication has not been performed correctly.

Then, when it is determined that the UDP communication has not been performed correctly, the correction unit corrects the command value used for the current control to a value obtained by multiplying the speed of the conveying device by the control cycle. In other words, the correction unit corrects the command value to a value estimated from the speed of the conveying device when the UDP communication fails.

As a result, even if the UDP communication fails, it is possible to control the movement of the robot on the slave side by following the movement of the conveying device, that is, the movement of the workpiece, which is not actually stopped. That is, it becomes possible to improve the followability of tracking.

By the way, the transmission of the command value and speed information of the conveying device as control information, more specifically, the selection of the speed information as the data to be transmitted together with the command value has important technical implications as described below. meaning exists.

First, the speed information is data that is originally used for control by the control device on the master side, and is data that is obtained without new processing. With only one piece of speed information, the control device on the slave side independently determines whether or not the UDP communication has been performed correctly, and handles the case where the UDP communication has not been performed correctly. I will be able to do it.

Therefore, if control information is transmitted with one piece of speed information added, even if UDP communication is not performed correctly, correction can be performed only by the control device on the slave side without performing processing such as retransmission. Therefore, the processing load and communication load of the control device on the master side are not increased. Therefore, in the robot system, among various parameters for controlling the robot, speed information is selected as data to be transmitted as control information.

With such a configuration, the robot system can reduce the load on the master-side control device and the load on the slave-side control device, and the slave-side control device alone can determine whether UDP communication has been performed correctly. can be determined and a countermeasure can be taken when the UDP communication is not performed correctly.

At this time, even if the number of slave-side controllers increases or decreases, the robot system basically does not change the processing of the master-side controller. You can also plan.

According to the second aspect of the present invention, in the robot system, the determination section sets the reference value to zero. This makes it possible to easily determine whether or not the transport device is actually moving. Therefore, an excessive increase in the load on the slave-side control device can be suppressed.

In the invention recited in claim 3, the storage unit stores a plurality of pieces of speed information used for control as a history, the correction unit obtains the trend of change in the speed of the conveying device from the history stored in the storage unit, The command value is corrected in consideration of the change tendency of the speed. For example, when the speed of the transport device tends to increase, it is corrected by multiplying by a coefficient larger than 1, and when the speed of the transport device tends to decrease, it is corrected by multiplying by a coefficient smaller than 1. Correction can be performed in correspondence with the actual speed change of the device, and follow-up performance during tracking can be further improved.

In the fourth aspect of the invention, the speed information generator of the control device on the master side converts the command value sent this time to the drive shaft of the conveying device into a pulse value and the command value sent last time into a pulse value. A pulse difference value, which is the difference from the value obtained by the measurement, is transmitted as speed information. This pulse difference value is data used in the control of the control device on the master side, and is a value obtained without performing new processing. Also, since the pulse difference value is data obtained as an integer, the amount of data required for transmission can be reduced compared to the case where the speed itself including the decimal point is transmitted. Therefore, the communication load can be further reduced.

According to the fifth aspect of the present invention, in a robot system that performs additional axis tracking for collectively controlling the operation of the transfer device and the robot, the slave-side control device receives signals from the master-side control device that controls the transfer device. It operates based on the control information, and has the above-described communication unit, storage unit, determination unit, and correction unit.

Even with such a robot control device, while reducing the load on the master side control device and the load on the slave side control device, and the slave side control device alone, it is possible to check whether the UDP communication is correctly performed. It is possible to obtain the same effects as those of the above-described robot system, such as being able to determine whether UDP communication is performed correctly, and to take measures when UDP communication is not performed correctly.

1 is a diagram schematically showing the configuration of a robot system according to an embodiment; FIG. A diagram schematically showing the electrical configuration of the robot system Diagram for explaining the outline of additional axis tracking FIG. 4 is a diagram for explaining an outline of the processing of the slave-side control device; Schematic diagram showing an example of robot speed without and with correction Diagram schematically showing the flow of processing by the slave-side control device

Hereinafter, embodiments will be described with reference to the drawings.
As shown in FIG. 1, the robot system 1 of this embodiment performs the above-described additional axis tracking for collectively controlling the transport device 2 and the motion of the robot. A device 3, a master robot 4 controlled by the master controller 3, one or more slave controllers 5 communicatively connected to the master controller 3, and the slave controllers 5, respectively. and one or more slave-side robots 6 to be controlled.

The master-side control device 3 includes a motor 7 for driving the conveying device 2, an encoder 8 provided in the motor 7, and a camera or laser rangefinder for detecting the position of the workpiece 9 conveyed by the conveying device 2. device 10 is connected. A rotating shaft of the motor 7 serves as a driving shaft of the conveying device 2 . In other words, the robot system 1 is configured to perform additional axis tracking using the rotation axis of the motor 7 to be controlled, which is different from the drive axis of the joint of the master robot 4, as an additional axis.

A hub 12 is connected to the master side control device 3 via a LAN line 11, and is configured to be able to communicate with a slave side control device 5 connected therefrom. Although FIG. 1 shows a configuration example in which two slave side control devices 5 are connected, it is of course possible to connect one or three or more slave side control devices 5. The robot system 1 in the form can be connected to several tens of slave-side control devices 5 .

The slave-side controller 5 controls each slave-side robot 6 . In this embodiment, the master-side robot 4 and the slave-side robot 6 are assumed to be horizontal multi-joint type so-called four-axis robots, but vertical multi-joint type so-called six-axis robots, seven-axis robots, or a combination thereof. can also be targeted. FIG. 1 illustrates a configuration in which a plurality of slave robots 6 are installed downstream of the master robot 4 in the transport direction of the transport device 2. is not limited to

Now, as shown in FIG. 2, the master-side control device 3 includes a command value generating section 3a, a speed information generating section 3b, a communication section 3c, and the like. The command value generator 3 a generates command values for controlling the master robot 4 and command values for driving the transport device 2 . At this time, the command value given to the transport device 2 is a value indicating the target position of the transport device 2, in simple terms. can be estimated.

In the following, for the sake of simplification of explanation, simply referring to a command value means a command value given to drive the transport device 2, and the command value for controlling the robot is It is called a control command value.

The speed information generation unit 3b generates information that can specify the speed of the conveying device 2, that is, the moving speed of the workpiece 9, details of which will be described later. In this embodiment, as the speed information, a pulse difference value, which is a difference between a value obtained by converting the command value sent this time to the drive shaft of the conveying device 2 into a pulse value and a value obtained by converting the command value sent last time into a pulse value, is used. I am using The command value generation unit 3a and the speed information generation unit 3b are realized by software by executing programs in a CPU (not shown).

The communication unit 3c is a so-called LAN interface, and communicates with the slave side control device 5 via the LAN line 11, such as control information, which is a communication packet containing a command value and speed information to be given to the conveying device 2. conduct. Although the details will be described later, the communication unit 3c can perform UDP communication and TCP communication. 2, illustration of the hub 12 is omitted.

The slave-side control device 5 includes a command value generation section 5a, a determination section 5b, a correction section 5c, a storage section 5d, a communication section 5e, and the like. The command value generator 5 a generates a control command value for controlling the slave robot 6 . Although details will be described later, the determination unit 5b determines whether or not UDP communication with the master-side control device 3 has been performed correctly.

Although the details will be described later, the correction unit 5c corrects the command value used in the current control when the determination unit 5b determines that the UDP communication with the master-side control device 3 has not been performed correctly. The command value generating unit 5a, the determining unit 5b, and the correcting unit 5c are realized by software by executing programs in a CPU (not shown).

The communication unit 5 e receives control information transmitted from the master-side control device 3 . Although the details will be described later, the communication unit 5e can also communicate information other than the control information. Although details will be described later, the storage unit 5d stores at least the received command value and the command value used in the previous control. At this time, control information including command values and speed information can also be stored in the storage unit 5d. In this embodiment, it is assumed that the storage unit 5d is not a non-volatile storage medium in which the main program of the slave-side control device 5 is stored, but a storage area provided on a memory such as a RAM. .

Next, the operation of the configuration described above will be described.
First, with reference to FIGS. 3 to 5, an outline of processing in additional axis tracking and problems occurring in the slave-side control device 5 will be described. Further, in the following, for the sake of simplification of explanation, when describing the common control device for the master-side control device 3 and the slave-side control device 5, it will simply be referred to as a control device, and the control device common to the master-side robot 4 and the slave-side robot 6 We will simply refer to it as a robot when explaining what it does.

As shown in FIG. 3 , the control device first identifies the position (E0) of the work 9 being transported by the transport device 2 . This E0 can be specified based on the position detected by the detector 10 in the case of the master side control device 3, and can be specified by the position data transmitted from the master side control device 3 in the case of the slave side control device 5.

Also, this E0 is a reference position during one tracking, and each control device performs tracking by adding the amount of movement by the conveying device 2 to this E0. Hereinafter, E0 will be referred to as a reference position for convenience. The reference position that serves as a reference for tracking is transmitted to the slave-side control device 5 by TCP communication that guarantees data reliability. However, since the reference position does not change during one tracking, it only needs to be transmitted once at the beginning of one tracking, and will not be repeatedly transmitted.

Now, assuming that the specified reference position is (x0, y0, z0) in the robot coordinate system, the control device generates a control command value (Ptask) for the robot at the standby position to operate with the reference position as the target. do. Hereinafter, for the sake of convenience, the movement of the robot with the reference position as the target will be referred to as the work movement. In addition, the control command value (Ptask) is also referred to as a work operation control command value.

Subsequently, the control device obtains the amount of movement (ΔConv) of the transport device 2 after the start of the work operation based on the command value of the transport device 2 . In this case, the master-side control device 3 uses the command value generated by itself to obtain the movement amount (ΔConv), and the slave-side control device 5 uses the command value transmitted from the master-side control device 3. is used to obtain the amount of movement (ΔConv).

Then, the control device generates a new control command value (Prob) by offsetting the control command value (Ptask) generated when the work operation is started by the amount of movement (ΔConv) in the conveying direction, and generates a new control command value (Prob). The robot is controlled to follow the workpiece 9 using the value (Prob). In this manner, tracking is performed in which the robot is caused to work while following the movement of the workpiece 9 .

By the way, in order to improve the followability of tracking, it is conceivable that the command value for obtaining the movement amount (ΔConv) of the conveying device 2 should be generated at a finer cycle. Therefore, the master-side control device 3 generates a command value for the transport device 2 for each control cycle (ΔT), and transmits the generated command value to the slave-side control device 5 each time. This control cycle (ΔT) is approximately several milliseconds.

However, as the number of slave-side control devices 5 increases, it becomes difficult to perform one-to-one TCP communication with each slave-side control device 5 every control cycle (ΔT). This is because in the case of TCP communication, a handshake is required to ensure data reliability, and processing such as retransmission may be required in some cases. Therefore, in the present embodiment, the master-side control device 3 employs UDP communication using UDP (User Datagram Protocol) to transmit the command values of the transport devices 2 to be transmitted to the slave-side control devices 5 all at once. .

As a result, although UDP communication, which is so-called connectionless communication, does not guarantee the reliability of the data itself, it enables one-to-many communication with a greatly reduced communication load compared to TCP communication.

On the other hand, adopting UDP communication causes problems in the slave-side control device 5 . Specifically, as shown in FIG. 4, when the communication unit 5e of the slave-side control device 5 receives the command value from the master-side control device 3 through UDP communication, it stores the command value in the storage area as the latest data. This storage area corresponds to the storage unit 5d. Although the details will be described later, the command value and speed information are stored in the latest data. Also, the past data shown in FIG. 4 will be described later.

Subsequently, the command value generation unit 5a of the slave-side control device 5 reads the command value stored in the storage area as the latest data, obtains the movement amount (ΔConv) of the conveying device 2 based on the read command value, A new control command value (Prob) offset by the obtained movement amount (ΔConv) is generated and output to the slave robot 6 to control the slave robot 6 .

In this case, when the UDP communication is correctly performed, the command value most recently transmitted from the master-side control device 3 is stored as the latest data in the storage area. On the other hand, if the UDP communication is not performed correctly, the latest data in the storage area will not update the command value due to failure in reception, and the previously received command value will be stored as it is. Become.

Then, the command value generator 5a of the slave-side control device 5 generates a control command value to be given to the slave-side robot 6 based on the command value stored as the latest data regardless of whether the UDP communication has been performed correctly. Since the control command value is generated and output, if the UDP communication is not performed correctly, the control command value to be given to the slave robot 6 is generated based on the same command value used in the previous control.

Here, the command value for the conveying device 2 indicates the target position as described above. Therefore, the state in which the latest data in the storage area has not been updated means the state in which the target position is the same as the previous time, that is, the state in which the conveying device 2 is stopped. Therefore, the slave-side control device 5 determines that the transfer device 2 is stopped, and generates a control command to decelerate or stop the slave-side robot 6 .

As a result, as shown by graph G1 in FIG. 5, it is assumed that the actual speed of the conveying device 2 is a constant value Vc. Then, for example, if the UDP communication is not performed correctly at time t0, the slave-side control device 5 calculates the speed of the transport device 2 based on the command value used in the previous control as described above. It is determined that the device 2 has stopped. As a result, as shown in the graph G3 as a comparative example, control is performed to stop or decelerate the slave robot 6, so that the speed of the slave robot 6 decreases and cannot follow the movement of the transport device 2. .

Then, assuming that the UDP communication is correctly performed at time t1, the slave-side control device 5 obtains the speed of the transport device 2 based on the updated command value. In this case, assuming that the period from time t0 to time t1 is one control cycle (ΔT), the target position of the conveying device 2 that is not actually stopped is two control cycles (2ΔT) later. , the slave-side control device 5 moves the slave-side robot 6 at high speed.

Further, when the UDP communication is correctly performed at time t2, the slave-side control device 5 causes the slave-side robot 6 to move a distance of one control cycle (ΔT) based on the latest command value. Decrease speed.

In this way, when UDP communication is used to reduce the load on the master-side control device 3, there is a risk that the speed of the slave-side robot 6 will change discontinuously. Such an operation may cause the robot to vibrate, resulting in problems such as a longer operation cycle.

However, inquiring the master side control device 3 about the success or failure of UDP communication or requesting retransmission results in an increase in the load on the master side control device 3 and the slave side control device 5. This goes against the gist of adopting UDP communication in order to reduce

Therefore, in the present embodiment, while reducing the load on the master-side control device 3 and the load on the slave-side control device 5, the slave-side control device 5 alone determines whether or not the UDP communication has been correctly performed. , and measures to be taken when UDP communication is not performed correctly.

The slave-side control device 5 performs correction processing shown in FIG. Although this process is performed by the determination unit 5b and the correction unit 5c, the slave side control device 5 will be mainly described below for the sake of simplification of explanation.

First, the slave-side control device 5 generates a work operation control command value (Ptask) (S1). Since the control command value (Ptask) for the work motion does not change during tracking, the value generated for the first time can be reused. Subsequently, the slave-side control device 5 reads the latest data stored in the storage area to obtain the command value for the transport device 2 (S2). The correction value read out in step S2 corresponds to the correction value (Pnew) used in the current control.

Now, if the obtained command value is used as it is, the speed of the slave robot 6 will change discontinuously if the UDP communication is not performed correctly as described above. Therefore, the slave-side control device 5 determines whether or not the UDP communication is properly performed, and corrects the command value when the UDP communication is not properly performed. Further, in the robot system 1, determination and correction are made in a manner that reduces the communication load.

First, how to determine whether UDP communication is being performed correctly will be described. The slave-side control device 5 stores the command value used for control in the storage area each time as past data (see FIG. 4). It is determined whether or not the command value used in the previous control matches (S3). The past data can also store the speed information used in the previous control.

As described above, the command value is the target position of the conveying device 2. Therefore, if the command value used in the current control does not match the command value used in the previous control, the latest data has been updated. It can be determined that the UDP communication was performed correctly. Therefore, when the command value used in the current control and the command value used in the previous control do not match (S3: NO), the slave-side control device 5 proceeds to step S6 to (ΔConv) is obtained.

On the other hand, if the command value used for the current control and the command value used for the previous control match, the UDP communication was not performed correctly because the latest data was not updated. I have doubts. However, it cannot be completely denied the possibility that the UDP communication was performed correctly, such as when the master-side control device 3 sent the same command value due to an emergency stop or the like.

Therefore, when the command value used in the current control and the command value used in the previous control match (S3: YES), the slave-side control device 5 further increases the speed of the conveying device 2 used in the current control. exceeds a predetermined reference value (S4). In this embodiment, zero is used as the predetermined reference value. That is, in step S4, the slave-side control device 5 determines whether or not the speed of the conveying device 2 is zero.

Note that the speed of the conveying device 2 can be obtained based on speed information transmitted from the master-side control device 3 . In this case, since the latest data is not updated if the UDP communication is not performed correctly, the content of the latest data and the content of the past data storing the data used in the previous control match. . Therefore, in step S4, the most recent speed of the conveying device 2 can be obtained by using the speed information stored in either the latest data or past data.

When the slave-side control device 5 determines that the speed of the transport device 2 does not exceed the predetermined reference value (S4: NO), the process proceeds to step S6 to obtain the movement amount (ΔConv) of the transport device 2. . This is because when it is determined that the speed of the transport device 2 is zero, the command values of this time and the previous time match, so it can be considered that the transport device 2 is actually stopped. It's for.

On the other hand, when the slave-side control device 5 determines that the speed of the transport device 2 exceeds the predetermined reference value (S4: YES), it corrects the command value of the transport device 2 (S5). . If the previous and current command values match even though the speed of the conveying device 2 does not drop, it means that the latest data has not been updated, that is, the UDP communication has not been performed correctly. Because we can.

In step S5, the slave-side control device 5 converts the command value (Pnew) acquired in step S2 to (1) Correct as shown in the formula.
Pnew=Pnew+Vc×ΔT (1)

That is, the correction unit 5c of the slave-side control device 5 corrects the command value (Pnew) used in the current control to a value obtained by multiplying the speed (Vc) of the conveying device 2 by the control cycle (ΔT). . It should be noted that correction is necessary when the previous and current command values match, that is, when Pnew=Pprev, so the above equation (1) can be expressed as follows. can also

As a result, the command value used in the previous control is corrected to match the value corresponding to the speed of the conveying device 2, that is, the new target position in consideration of the amount of movement of the conveying device 2. FIG. Therefore, it is possible to prevent the slave robot 6 from erroneously stopping or decelerating in a situation where the speed of the transport device 2 is not zero, that is, in a situation where it can be determined that the workpiece 9 is moving.

Then, the slave-side control device 5 obtains the movement amount of the conveying device 2 based on the corrected command value (S6). That is, the final control command value used for the current control is generated (S7). As a result, the slave-side control device 5 can avoid stopping or decelerating the slave-side robot 6 by mistake.

As a result, as shown in graph G4 shown as an example in FIG. (Vc), that is, the actual movement of the workpiece 9 is followed.

By performing such correction, it is possible to determine whether or not UDP communication is being performed correctly, and to take measures when UDP communication is not being performed properly. The correction method described above also has the effect of reducing the communication load.

For example, if it is only necessary to determine whether or not UDP communication is being performed correctly, it is conceivable to add a serial number and time information to the communication packet sent from the master-side control device 3. However, in that case, Although it can be determined that the UDP communication is not performed correctly, it becomes impossible to deal with it.

However, requesting retransmission of the command value increases the communication load, which goes against the purpose of using UDP communication as described above. In addition, each control device manages the time individually, and the time is not necessarily completely synchronized. Therefore, even if the time information is used, it cannot be determined whether UDP communication is being performed correctly. It is possible.

Therefore, the data transmitted from the master-side control device 3 is desired to be able to determine whether or not UDP communication is being performed properly, and to take action when UDP communication is not performed properly. . On the other hand, if the size of data to be transmitted increases, there is a risk of increasing the communication load.

Therefore, in the present embodiment, in addition to the command value to be given to the conveying device 2 that is necessary for the original control, speed information that can specify the speed of the conveying device 2 is included in the communication packet and transmitted. By transmitting these command values and speed information from the master side control device 3, the slave side control device 5 determines whether or not the UDP communication is being performed correctly, and determines whether the UDP communication is being performed correctly. It is possible to deal with the case where it is not broken.

In other words, the speed information of the conveying apparatus 2 alone can determine whether or not UDP communication is being performed correctly, and deal with the case where UDP communication is not being properly performed. This data is considered to be suitable for making determinations and taking measures while reducing .

Further, the speed of the transfer device 2 is information managed by the master-side control device 3, and is used to control the master-side robot 4. Therefore, new data is generated for determination and handling. and the processing load of the master-side control device 3 is not increased. In other words, the configuration in which the speed information is used as the data transmitted from the master-side control device 3 has a very important technical significance in the robot system 1 .

Furthermore, in this embodiment, the speed information is the difference between the value obtained by converting the command value sent to the drive shaft this time into the pulse value of the encoder 8 and the value obtained by converting the command value sent last time into the pulse value of the encoder 8. A pulse difference value is adopted. When attempting to transmit the speed of the conveying device 2 itself, if the position is controlled with high precision, a decimal point is inevitably included. It is necessary to send 8-byte data of double type.

On the other hand, the pulse difference value is obtained as integer data, and when it is transmitted as a communication packet, it can be transmitted as long-type 4-byte data in C language. That is, by using the pulse difference value of the encoder 8 as the speed information, the data size required for determination and handling can be reduced, and the communication load can be suppressed.

After generating the control command value used for the current control in this way, the slave-side control device 5 stores the command value obtained in step S2 as past data in the storage area. This stored past data is used for determination in the next control. At this time, not only the command value but also the speed information may be stored in the storage unit 5d.

In FIG. 6, the processing is terminated for the sake of simplification of explanation, but during tracking, the processing after step S2 is repeatedly executed manually as necessary.

As described above, the robot system 1 of the present embodiment reduces the load on the master-side control device 3 and the load on the slave-side control device 5, and allows the slave-side control device 5 to perform UDP communication correctly. It is configured to be able to determine whether or not the UDP communication has been successfully performed, and to take action when the UDP communication is not properly performed.

According to the embodiment described above, the following effects can be obtained.
The robot system 1 performs additional axis tracking that collectively controls the transport device 2 and the motion of the robot, and is controlled by the master-side controller 3 that controls the transport device 2 and the master-side controller 3. a master-side robot 4, one or more slave-side controllers 5 communicably connected to the master-side controller 3, one or more slave-side robots 6 controlled by the slave-side controllers 5, It has

The master-side control device 3 includes a command value generation unit 5a that generates a command value to be given to the transport device 2, a speed information generation unit 3b that generates speed information that can specify the speed of the transport device 2, and the generated command value and and a communication unit 5e for transmitting speed information as control information to the slave side control device 5 by UDP communication. By adopting a configuration in which control information is transmitted by UDP communication in this manner, the load required for communication can be greatly reduced compared to TCP communication, which requires handshake.

Further, the slave-side control device 5 includes a communication unit 5e that receives control information transmitted from the master-side control device 3, a storage unit 5d that stores control information used in the previous control, and the master-side control device 3. When it is determined by the determination unit 5b that the determination unit 5b determines whether the UDP communication between is performed correctly, and the determination unit 5b that the UDP communication between the master-side control device 3 was not performed correctly, this control and a correction unit 5c for correcting the command value used for.

The determination unit 5b determines whether the command value used in the current control and the command value used in the previous control match and the speed of the conveying device 2 used in the current control exceeds a predetermined reference value. If so, it is determined that the UDP communication with the master-side control device 3 was not performed correctly, and the correction unit 5c multiplies the command value used for this control by the speed of the conveying device 2 and the control period. corrected to the added value.

By transmitting the command value and speed information as control information in this manner, the slave-side control device 5 can independently determine whether or not the UDP communication has been performed correctly, and if the UDP communication has not been performed correctly. It is possible to deal with the case. In other words, by adopting the speed information as the control information to be transmitted, it becomes possible to perform the above-described determination and countermeasures with one piece of data.

At this time, the speed information is data used in the control of the master-side control device 3, and is a value obtained without performing new processing. In addition, since it is only necessary to add one piece of data called speed information to the command value originally required for control, the load on the master side control device 3 is not increased, and the load required for communication is excessively increased. can be reduced.

Therefore, while reducing the load on the master-side control device 3 and the load on the slave-side control device 5, the slave-side control device 5 alone can determine whether or not the UDP communication has been performed correctly, and the UDP communication can be performed correctly. If it is not done, it can be dealt with.

Further, by performing the above correction, it is possible to improve the followability of tracking. Furthermore, even if the number of slave-side control devices 5 increases or decreases, the processing of the master-side control device 3 basically does not change, so that flexibility and expandability of the system can be ensured.

Further, in the robot system 1, the determination unit 5b sets the reference value to zero. This makes it possible to easily determine whether or not the transport device 2 is actually moving.

In the robot system 1, the speed information generator 3b of the master-side control device 3 converts the command value sent this time to the drive shaft of the transport device 2 into the pulse value of the encoder 8, and the command value sent last time. 8 is transmitted as speed information. The pulse difference value of the encoder 8 is data used in the control of the master-side control device 3, and is a value obtained without new processing. Also, since the pulse difference value is data obtained as an integer, the amount of data required for transmission can be reduced compared to the case where the speed itself including the decimal point is transmitted. Therefore, the communication load can be further reduced.

In addition, in the robot system 1 that performs additional axis tracking for collectively controlling the transport device 2 and the motion of the robot, the slave-side control device 5 responds to the control information transmitted from the master-side control device 3 that controls the transport device 2. It has the communication unit 5e, the storage unit 5d, the determination unit 5b, and the correction unit 5c. Even with such a robot control device, while reducing the load on the master side control device 3 and the load on the slave side control device 5, and the slave side control device 5 alone, it is possible to check whether the UDP communication was correctly performed. It is possible to obtain the same effects as those of the robot system 1, such as being able to determine whether the UDP communication is performed correctly, and to take measures when the UDP communication is not performed correctly.

In the embodiment, the command value is corrected using the formula (1). It is also possible to adopt a configuration in which the command value is corrected in consideration of the change tendency of the speed. For example, a coefficient (α) is added to the second term on the right side of equation (1), and when the speed of the transport device 2 tends to increase, α is set to be greater than 1, and when it tends to decrease, α is set to By setting it to be smaller than 1, it is possible to perform correction in accordance with the actual speed change. Note that α can also be a function of velocity.

Although an example in which the predetermined reference value is set to zero has been shown in the embodiment, it is determined that the predetermined reference value does not cause the speed to become zero in one control cycle based on the performance and specifications of the conveying device 2, for example. can be set to any possible value.

Although the example in which the predetermined reference value is a fixed value has been shown in the embodiment, the predetermined reference value can also be changed. For example, if it is moving relatively fast, it will take a certain amount of time to stop, so set a higher reference value, and if it is moving relatively slowly, wait until it stops. Since it is assumed that the period of time is shortened, it is possible to set the reference value to be low. Alternatively, past speed information is stored as a history in the storage unit 5d, and when the speed of the conveying device 2 tends to increase, the reference value is set higher, and when it tends to decrease, the reference value is set lower. can also be configured to be set to

Although the example in which the command value is transmitted in each control cycle (ΔT) for generating the command value has been shown in the embodiment, it is also possible to transmit the command value multiple times within the cycle in which the command value is generated.
The robot system 1 can also be applied to a configuration in which one master-side control device 3 controls a plurality of transfer devices 2 .

Although the example in which the pulse difference value of the encoder 8 is transmitted as speed information has been shown in the embodiment, the speed acquired by a speedometer that detects the speed of the conveying device 2 can also be transmitted as speed information.
The above-described embodiments are merely examples, and are not intended to limit the technical scope of the present invention.

In the drawing, 1 is a robot system, 2 is a transport device, 3 is a master side control device (master side control device), 3a is a command value generation unit, 3b is a speed information generation unit, 3c is a communication unit, and 4 is the master side. A robot (master-side robot), 5 a slave-side control device (slave-side control device), 5a a command value generation unit, 5b a determination unit, 5c a correction unit, 5d a storage unit, 5e a communication unit, 6 denotes a slave-side robot (slave-side robot), 7 a motor (additional axis), and 8 an encoder.

Claims (5)

A robot system that performs additional axis tracking for collectively controlling the operation of a transport device and a robot,
a master-side control device that controls the conveying device;
a master-side robot controlled by the master-side control device;
one or more slave-side control devices communicably connected to the master-side control device;
one or more slave-side robots each controlled by the slave-side controller,
The control device on the master side,
a command value generation unit that generates a command value to be given to the conveying device;
a speed information generating unit that generates speed information that can identify the speed of the conveying device;
a communication unit that transmits the generated command value and speed information as control information to the control device on the slave side by UDP communication;
The control device on the slave side,
a communication unit that receives control information transmitted from the control device on the master side;
a storage unit that stores the command value used in the previous control;
a determination unit that determines whether UDP communication with the master-side control device has been performed correctly;
a correction unit that corrects a command value used for current control when the determination unit determines that UDP communication with the control device on the master side has not been performed correctly,
The judging unit determines that when the command value used in the current control matches the command value used in the previous control and the speed of the conveying device used in the current control exceeds a predetermined reference value. If there is, it is determined that the UDP communication with the control device on the master side was not performed correctly,
The robot system, wherein the correcting unit corrects the command value used in the current control to a value obtained by multiplying the speed of the conveying device by the control cycle. 2. The robot system according to claim 1, wherein the determination unit sets the reference value to zero. The storage unit stores a plurality of pieces of speed information used for control as a history,
2. The robot system according to claim 1, wherein the correcting unit obtains a tendency of change in speed of the conveying device from the history stored in the storage unit, and corrects the command value in consideration of the tendency of change in speed. The speed information generation unit of the control device on the master side converts the command value sent this time to the drive shaft of the transport device into an encoder pulse value, and the command value sent last time into an encoder pulse value. 4. The robot system according to any one of claims 1 to 3, wherein a pulse difference value which is a difference between and is transmitted as velocity information. In a robot system that performs additional axis tracking that collectively controls the operations of a transport device and a robot, a control device for a slave-side robot that operates based on control information transmitted from a master-side control device that controls the transport device. and
The control device on the master side sends, as control information, a command value to be given to the transfer device and speed information capable of specifying the speed of the transfer device to all the control devices on the slave side connected simultaneously by UDP communication. send and
a communication unit that receives control information transmitted from the control device on the master side;
a storage unit that stores the command value used in the previous control;
a determination unit that determines whether UDP communication with the master-side control device has been performed correctly;
a correction unit that corrects a command value used for current control when the determination unit determines that UDP communication with the control device on the master side has not been performed correctly,
The judging unit determines that when the command value used in the current control matches the command value used in the previous control and the speed of the conveying device used in the current control exceeds a predetermined reference value. If there is, it is determined that the UDP communication with the control device on the master side was not performed correctly,
The correction unit corrects the command value used in the current control to a value obtained by multiplying the speed of the conveying device by the control cycle.

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