Robot control system and power failure monitoring circuit

Abstract

To enable quick detection of occurrence of power failure so as to contribute to cost reduction and suppression of increase in size of a power supply module.SOLUTION: A robot controller is provided with a power failure monitoring circuit 68 for monitoring a power failure. The power failure monitoring circuit 68 includes: a rectifier 72 that rectifies power (AC) supplied from an external power supply to input terminals 71a and 71b of the power failure monitoring circuit 68; a photocoupler 73 that converts the power rectified by the rectifier 72 into light to generate a pulse signal oscillating at a fixed period; and a monitoring signal generator 74 that generates a power failure monitoring signal on the basis of the pulse signal generated by the photocoupler 73. When a time that the pulse signal is at a LOW level reaches a determination reference time, the monitoring signal generator 74 outputs, to a digital port of a drive control unit 62, as the power failure monitoring signal, a power failure detection signal indicating occurrence of the power failure. A CPU of the drive control unit 62 executes power failure addressing processing on the basis of reception of the power failure detection signal.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a robot control system and a power failure monitoring circuit applied to a robot control system. [Background technology]

[0002] Some robot control systems that perform drive control of industrial robots are equipped with an auxiliary power supply in case the power supply from the external power supply is suddenly stopped, i.e., in the event of a power outage. In this type of robot control system, when a power outage occurs, power is supplied from the auxiliary power supply instead of the external power supply, and some are configured to perform stop control for stopping the robot normally while power is being supplied from the auxiliary power supply, control for saving the position of the robot and the execution status of the control program, etc. For example, in a robot controller described in Patent Document 1, a technology is proposed for performing stop control of the robot during an operation period using the charged charge of a smoothing capacitor as a power source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-213854 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when taking the above-mentioned power outage countermeasures, the power consumption of the auxiliary power supply increases as the time lag between the actual occurrence of a power outage and the detection of the occurrence of the power outage and the start of the above-mentioned processing to deal with the power outage increases. In other words, in order to properly function the power outage countermeasures, it becomes necessary to estimate such power consumption in the capacity of the auxiliary power supply, and as a result, the capacity required for the auxiliary power supply increases. The increase in the capacity of the auxiliary power supply leads to an increase in the cost of the power supply module and an increase in the size of the power supply module. Furthermore, the increase in the size of the power supply module can be an obstacle to miniaturization of the object on which the power supply module is mounted (industrial robot or robot controller) and coexistence with other components around the power supply module.

[0005] The present invention has been made in consideration of the problems exemplified above, and its main object is to contribute to reducing the cost and size of power supply modules by making it possible to quickly detect the occurrence of a power outage. [Means for solving the problem]

[0006] Means for solving the above problems will be described below.

[0007] First means: A robot control system for controlling an industrial robot, An input terminal to which power is supplied from an external power source which is an AC power source; a pulse signal generating unit that generates a pulse signal that has a first value when an input voltage to the input terminal is higher than a specific voltage and that has a second value when the input voltage is lower than the specific voltage; a power failure response processing execution unit that executes a power failure response processing when a value of the pulse signal generated by the pulse signal generation unit is the second value for a predetermined period of time; It is equipped with:

[0008] According to the first means, a pulse signal is generated from the power (AC) supplied from the external power source. This pulse signal periodically changes between a first value and a second value in a situation where the power supply from the external power source continues. Then, when a power outage occurs, the pulse signal maintains the second value, so that the power outage can be detected from the period during which the pulse signal is at the second value. In this means, when the value of the pulse signal is at the second value for a predetermined period, it is determined that a power outage has occurred, and a power outage response process is executed. For example, since it is not necessary to take measures such as analyzing an analog signal to detect a power outage, it can contribute to shortening the period required for detection. In addition, since it is not configured to monitor the operating power converted to DC, it is not necessary to smooth using a capacitor or the like. Therefore, it is possible to avoid delays in power outage detection due to smoothing. For the above reasons, it is possible to shorten the period from when a power outage actually occurs to when a power outage is detected and the period from when a power outage is detected to when a power outage response process is executed. This is preferable in terms of reducing the capacity of the auxiliary power source for use during a power outage mounted in the robot control system, and reducing the cost and suppressing the increase in size of the power source module having the auxiliary power source.

[0009] Second means: A power failure monitoring circuit applied to a robot control system for controlling an industrial robot, An input terminal to which power is supplied from an external power source which is an AC power source; a pulse signal generating unit that generates a pulse signal that has a first value when an input voltage to the input terminal is higher than a specific voltage and that has a second value when the input voltage is lower than the specific voltage; a power failure detection signal generating unit that generates a power failure detection signal when a value of the pulse signal generated by the pulse signal generating unit is the second value for a predetermined period of time, and is capable of outputting the power failure detection signal to a control unit in the robot control system; It is equipped with:

[0010] According to the second aspect, the period from when a power outage actually occurs until when the power outage is detected can be shortened. This is preferable in terms of reducing the capacity of the auxiliary power supply for use during a power outage mounted in the robot control system, and reducing the cost and preventing the size of the power supply module having the auxiliary power supply. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a robot system. [Diagram 2] FIG. 2 is a block diagram showing the electrical configuration of the robot system. [Diagram 3] 5 is a flowchart showing a power failure process executed by a CPU of a drive control unit. [Figure 4] FIG. 1 is a schematic diagram for explaining a problem. [Diagram 5] FIG. 1 is a schematic diagram illustrating a conventional power outage monitoring circuit. [Figure 6] FIG. 1 is a schematic diagram showing a power outage monitoring circuit. [Figure 7] FIG. 4 is a schematic diagram showing a flow of generation of a power outage monitoring signal. [Figure 8] FIG. 4 is a schematic diagram showing a flow of generation of a power outage monitoring signal. [Figure 9] FIG. 4 is a schematic diagram showing a flow of generation of a power outage monitoring signal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment embodied as a robot system for use in a factory or the like will be described with reference to the drawings.

[0013] 1, the robot system 10 includes a robot 15, which is a vertical articulated industrial robot. The main body (robot main body 21) of the robot 15 includes a base 22 fixed to a pedestal or the like, a shoulder 23 supported by the base 22, a lower arm 24 supported by the shoulder 23, a first upper arm 25 supported by the lower arm 24, a second upper arm 26 supported by the first upper arm 25, a wrist 27 supported by the second upper arm 26, and a flange 28 supported by the wrist 27.

[0014] The base portion 22 and the shoulder portion 23 are formed with a first joint portion that connects the base portion 22 and the shoulder portion 23, and the shoulder portion 23 is rotatable in the horizontal direction around the connecting axis (first axis AX1) of the first joint portion. The shoulder portion 23 and the lower arm portion 24 are formed with a second joint portion that connects the shoulder portion 23 and the lower arm portion 24, and the lower arm portion 24 is rotatable in the vertical direction around the connecting axis (second axis AX2) of the second joint portion. The lower arm portion 24 and the first upper arm portion 25 are formed with a third joint portion that connects the lower arm portion 24 and the first upper arm portion 25, and the first upper arm portion 25 is rotatable in the vertical direction around the connecting axis (third axis AX3) of the third joint portion. The first upper arm portion 25 and the second upper arm portion 26 are formed with a fourth joint portion that connects the first upper arm portion 25 and the second upper arm portion 26, and the second upper arm portion 26 is rotatable in a twisting direction around the connecting axis (fourth axis AX4) of the fourth joint portion. The second upper arm portion 26 and the wrist portion 27 are formed with a fifth joint portion that connects the second upper arm portion 26 and the wrist portion 27, and the wrist portion 27 is rotatable in a vertical direction around the connecting axis (fifth axis AX5) of the fifth joint portion. The wrist portion 27 and the flange portion 28 are formed with a sixth joint portion that connects the wrist portion 27 and the flange portion 28, and the flange portion 28 is rotatable in a twisting direction around the connecting axis (sixth axis AX6) of the sixth joint portion.

[0015] The shoulder section 23, lower arm section 24, first upper arm section 25, second upper arm section 26, wrist section 27, and flange section 28 are arranged in a series to form an arm in the robot body 21, and an end effector 29 (e.g., a hand) is attached to the flange section 28 that forms the tip of the arm. The arm is provided with a servo motor for driving each joint, a rotary encoder for detecting the rotation angle of each joint (axis), and a non-excitation operated electromagnetic brake for each joint.

[0016] 2, the servo motor 31, the rotary encoder 32, and the electromagnetic brake 33 are connected to a robot controller 61. The robot controller 61 is also connected to a host controller 51 (e.g., a teaching pendant or a personal computer) which constitutes a robot control system 50 together with the robot controller 61, and data communication is performed between the robot controller 61 and the host controller 51 via a communication interface.

[0017] The host controller 51 stores a control program that defines the work content, work order, etc. of the robot 15. When a drive control unit 62 (CPU 63) of the robot controller 61 receives an operation command based on the control program from the host controller 51, it controls the drive of each servo motor 31 of the robot body 21 and the end effector 29 based on the operation command and position data (i.e., encoder value indicating the rotation angle) obtained from the rotary encoder 32.

[0018] The robot controller 61 is provided with a power supply module 65 connected to an external power supply, which is a commercial power source. The power supply module 65 is provided with a power supply circuit 66 having a diode bridge that converts the power supplied from the external power supply from AC to DC and a smoothing capacitor, and the power from the external power supply is supplied to the drive control unit 62, the robot body 21, the end effector 29, etc. after being converted and smoothed by the power supply circuit 66. The power supply circuit 66 of the power supply module 65 is also provided with an auxiliary power supply 67 (internal power supply) which is a super capacitor that can supply power to the drive control unit 62, the robot body 21, the end effector 29, etc. in place of the external power supply when the power supply from the external power supply is cut off due to a power outage or the like.

[0019] The robot controller 61 is also provided with a power outage monitoring circuit 68 that monitors the occurrence of a power outage (detects a power outage). The power outage monitoring circuit 68 is connected to the drive control unit 62 separately from the power supply circuit 66, and the drive control unit 62 determines that a power outage has occurred based on a signal from the power outage monitoring circuit 68. Here, a power outage process executed as part of regular processing by the CPU 63 of the drive control unit 62 will be described with reference to the flowchart of FIG.

[0020] In the power outage processing, first in step S101, it is determined whether or not a power outage has occurred based on a signal from the power outage monitoring circuit 68 (hereinafter referred to as the "power outage monitoring signal"). Details will be described later, but the power outage monitoring signal is a binary signal that is normally ON (HIGH level) and is configured to be input to a digital port of the drive control unit 62. In step S101, the digital port is checked, and it is determined that a power outage has occurred if the power outage monitoring signal becomes OFF (LOW level). In the following explanation, the portion of the power outage monitoring signal that is at the LOW level is also referred to as the "power outage detection signal."

[0021] If it is determined that no power outage has occurred, i.e., if the power outage monitoring signal is at HIGH level, a negative determination is made in step S101 and the power outage processing ends. On the other hand, if the power outage monitoring signal is at LOW level, i.e., if a power outage detection signal has been received, a positive determination is made in step S101 and the power outage response processing of steps S102 to S105 is executed.

[0022] In the power failure response process, first, the power supply to some devices (for example, a display and a cooling fan) is stopped (step S102). This reduces power consumption and extends the time that the robot can operate using the auxiliary power supply 67. Next, a safe stop process is executed (step S103). In the safe stop process, the robot 15 is decelerated and stopped normally while avoiding some postures. After the robot 15 has stopped (step S104: YES), information on the current position (stop position) and the process (step) being executed in the control program are stored in the memory 64 of the drive control unit 62 (step S105). The memory 64 is non-volatile, and the stored information is retained even if the power supply from the auxiliary power supply 67 is interrupted.

[0023] When the power supply from the external power source is resumed, the system checks with the user whether or not to resume the operation of the robot 15 from the process where it was interrupted, and when the user gives an instruction to resume, the system executes processing for resuming operation based on the information on the stop position stored in the memory 64, etc.

[0024] Here, as described above, it is preferable to configure the robot 15 to be stopped normally by receiving power from the auxiliary power source 67 and to store information on the stopped position, etc., in order to improve the safety of the robot system 10 and facilitate the recovery work when the power supply is resumed. Here, if the capacity of the auxiliary power source 67 is increased, it becomes easier to secure the execution time of the power outage response process and the operation based on the process after a power outage, but such a configuration increases the exclusive area of ​​the auxiliary power source 67 in the robot controller 61. And it becomes difficult to coexist with other components constituting the robot controller 61, that is, peripheral components such as the drive control unit 62, the display, and the cooling fan. In other words, the increase in the size of the auxiliary power source 67 not only increases the cost, but can also be an obstacle to realizing the miniaturization of the robot controller 61 (power source module 65). In this embodiment, one of the features is that, in consideration of such circumstances, a measure is taken to suppress the dependency on the capacity of the auxiliary power source 67. Hereinafter, the problem that was focused on will be described first with reference to the timing chart of FIG. 4.

[0025] In the example shown in FIG. 4, a power outage occurs at the timing of ta1, and the power supply source is switched from the external power source to the auxiliary power source 67. However, at this point, the drive control unit 62 does not recognize the occurrence of the power outage, and the work (normal operation) of the robot 15 based on the control program continues. In other words, although for a short time, the power supplied from the auxiliary power source 67 is used for normal operation. At the timing of ta2 immediately after the power outage, the power outage monitoring circuit 68 detects the power outage, and the drive control unit 62 recognizes that a power outage has occurred. As a result, the above-mentioned power outage response process and the operation based on the process (power outage response operation) are started. Thereafter, the power outage response process and the like are completed at the timing of ta3, and the power supply from the auxiliary power source 67 is terminated at the timing of ta4 immediately after the power outage. In view of such behavior, if the time lag from the occurrence of a power outage to the detection of the power outage (recognition by the drive control unit 62) can be reduced, it can be said that this can contribute to reducing the power consumption of the auxiliary power source 67 before the power outage response process is started.

[0026] Here, we will give an example of a conventional power outage monitoring circuit (Fig. 5) and provide a supplementary explanation of the reason for the large time lag. In the example shown in Fig. 5, the power supplied from an external power source is input to an operational amplifier, and the signal output from the operational amplifier is input to an analog port of the drive control unit. The CPU of the drive control unit must analyze the signal input to the analog port to determine whether a power outage has occurred, so it takes a considerable amount of time to detect a power outage.

[0027] On the other hand, if the signal converted to DC by the power supply circuit is input to the digital port of the drive control unit, and the CPU of the drive control unit determines the falling edge of the signal from HIGH level to LOW level, it may be expected that the time lag will be shortened at first glance. However, since the power (DC) supplied from the power supply circuit is smoothed for the purpose of stable supply, the timing at which the signal falls to LOW level due to a power outage will be delayed. In other words, with such a configuration, it is practically difficult to shorten the time lag.

[0028] In this embodiment, the time lag is reduced by eliminating the inconveniences in the two power failure detection patterns. Below, the power failure monitoring circuit 68 in this embodiment will be described with reference to Figures 6 and 7. Figure 6 is a schematic diagram showing the power failure monitoring circuit 68 in this embodiment, and Figure 7 is a timing chart showing the flow of power failure monitoring signal generation.

[0029] The power supplied to the robot controller 61 from the external power source is distributed to a power supply circuit 66, an auxiliary power source 67, and a power failure monitoring circuit 68 at the input / output unit of the robot controller 61. As shown in FIG. 6, the power failure monitoring circuit 68 includes a rectifier 72 that rectifies the power (AC) supplied to the input terminals 71a and 71b of the power failure monitoring circuit 68, a photocoupler 73 that converts the power rectified by the rectifier 72 into light to generate a pulse signal with a constant period, and a monitoring signal generator 74 that is a logic circuit capable of generating the above-mentioned power failure monitoring signal based on the generated pulse signal. The power failure monitoring signal generated by the monitoring signal generator 74 is output to a digital port of the drive control unit 62.

[0030] The rectifier 72 is a full-wave rectifier (e.g., a diode bridge) that converts (inverts) the negative voltage portion of the input voltage to a positive voltage, and converts AC to DC (pulsating current) (see FIG. 7(a)→FIG. 7(b)). The power converted to DC by the rectifier 72 is supplied to a light-emitting portion 73a of a photocoupler 73.

[0031] Light from the light emitting unit 73a is irradiated to the light receiving unit 73b arranged to face the light emitting unit 73a. When the amount of light irradiated to the light receiving unit 73b exceeds a reference amount, a HIGH level signal is output from the light receiving unit 73b (i.e., the photocoupler 73 is turned ON), and when the amount of light is below the reference amount, a LOW level signal is output from the light receiving unit 73b (i.e., the photocoupler 73 is turned OFF). In other words, the power failure monitoring circuit 68 is electrically insulated (separated) into an input side and an output side by the photocoupler 73. In this way, it is preferable to immediately separate the power failure monitoring circuit 68 from the primary voltage using the photocoupler 73 in order to suppress the influence of a failure or the like.

[0032] The reference amount of light at which the photocoupler 73 turns ON, in other words the minimum operating voltage (threshold) of the light-receiving portion 73b, is determined by a resistor 78 disposed between the light-receiving portion 73b and the power source for the photocoupler 73. Specifically, the threshold is closer to the lower limit (0 V) of the voltage applied to the light-emitting portion 73a, and the period T1 during which the photocoupler 73 is ON is determined to be shorter than the period T2 during which it is OFF (see FIGS. 7(b) and 7(c)).

[0033] The monitoring signal generator 74 (specifically, a one-shot pulse generator) has a function of detecting a power outage from the ON / OFF state of the photocoupler 73, and generating the power outage detection signal when a power outage is detected. Specifically, the signal from the photocoupler 73 repeats ON / OFF at a constant cycle when the power supply from the external power source continues. In such a situation, the monitoring signal generator 74 outputs a HIGH level signal (ON signal) as a power outage monitoring signal. On the other hand, when the power supply from the external power source is stopped, the signal from the photocoupler 73 turns OFF. Then, when the signal from the photocoupler 73 remains OFF over the judgment reference period TX, the monitoring signal generator 74 outputs a power outage detection signal that is a LOW level signal (OFF signal) as a power outage monitoring signal. Specifically, the judgment reference period TX is set to be an integer multiple (specifically, three times) of the period by a plurality of resistors 79 provided in the pulse generator.

[0034] Here, a supplementary explanation will be given on the judgment reference period TX. In the external power supply, a momentary power outage (so-called momentary power outage) may occur, in which the voltage drops significantly instantaneously due to various factors. In this embodiment, a power outage with a length of one cycle at 50 / 60 Hz (20 msec for 50 Hz, 16.7 msec for 60 Hz) is assumed as the momentary power outage, but if the robot 15 is stopped every time such an event occurs, productivity may be greatly reduced. In this embodiment, the judgment reference period TX is set to be half a cycle longer (30 msec) than the time assumed for the momentary power outage (longer: 20 msec), making it difficult for such inconvenience to occur (improving immunity resistance). In other words, the pulse signal generated by the photocoupler 73 after full-wave rectification has one cycle of 10 msec, which is half that of AC, and the judgment reference period TX is set to be 30 mec, which is three times the cycle (10 msec) of this pulse signal.

[0035] In the example shown in Fig. 8, the power supply from the external power source is temporarily interrupted due to a momentary power outage. In this case, the photocoupler 73 remains OFF temporarily, but the power supply is resumed before the above-mentioned reference period TX has elapsed, turning the photocoupler 73 ON. As a result, the power outage monitoring signal remains at a HIGH level even during the period when the photocoupler 73 is OFF, and the output of the power outage detection signal due to the momentary power outage is prevented.

[0036] A capacitor is provided in the supply path of operating power to the monitoring signal generator 74 to prevent the power supply to the monitoring signal generator 74 from being interrupted in the event of a momentary power outage. In other words, a power outage detection signal (LOW level signal) is prevented from being erroneously output due to the power supply being interrupted and the power outage monitoring signal switching from HIGH level to LOW level. Incidentally, this is smaller than the servo motor 31 and the CPU 63 of the drive control unit 62 required for the operation (including signal generation) of the monitoring signal generator 74.

[0037] Next, referring to the example of FIG. 9, a case where a normal power outage occurs will be described. When a normal power outage occurs, the photocoupler 73 remains OFF for the judgment reference period TX. In the monitoring signal generator 74, the power outage monitoring signal is switched from HIGH level to LOW level at the timing when the judgment reference period TX has elapsed. In other words, a power outage detection signal is output. As a result, the voltage of the digital port of the drive control unit 62 falls. When this fall occurs, the CPU 63 of the drive control unit 62 determines that a power outage has occurred (step S101: YES above) and executes a power outage response process. This starts a power outage response operation.

[0038] According to the embodiment described above in detail, the following excellent effects can be expected.

[0039] The photocoupler 73 generates a pulse signal from the power (AC) supplied from the external power source. This pulse signal periodically changes between HIGH and LOW levels in a situation where the power supply from the external power source continues. When a power outage occurs, the pulse signal maintains a LOW level, so that the power outage can be detected from the period when the pulse signal is at a LOW level. The monitoring signal generator 74 shown in this embodiment generates a power outage detection signal when the pulse signal is at a LOW level over the judgment reference period TX, and this power outage detection signal is input to the digital port of the drive control unit 62. With this configuration, the CPU 63 of the drive control unit 62 does not need to take measures such as analyzing an analog signal to detect a power outage, which can contribute to shortening the period required for detection. In addition, since the configuration is not one that monitors the operating power converted to DC, there is no need to smooth using a capacitor or the like. Therefore, it is possible to avoid delays in power outage detection due to smoothing. For the above reasons, it is possible to shorten the period from when a power outage actually occurs to when a power outage is detected and the period from when a power outage is detected to when a power outage response process is executed. This is preferable in terms of reducing the capacity of the auxiliary power supply 67 installed in the robot control system 50 for use in the event of a power outage, and in terms of reducing the cost and preventing the size of the power supply module 65 that has the auxiliary power supply 67, and ultimately the robot controller 61.

[0040] Regarding the external power supply, a momentary power outage (a so-called momentary power outage with a length of one cycle (20 msec) at 50 / 60 Hz) may occur due to various factors, in which the voltage drops sharply for an instant. If the robot 15 is stopped every time a momentary power outage occurs, productivity may decrease significantly. Therefore, as shown in this feature, by setting the predetermined period to be longer than the length of one cycle of the pulse signal, it is possible to prevent the execution of a power outage response process in response to a momentary power outage.

[0041] As for the generated pulse signal, if the period when the signal is at a LOW level becomes dominant, the judgment reference period TX may become longer by setting the judgment reference period TX in consideration of the period when the signal is at a LOW level. This is not preferable in terms of reducing the time lag in detecting a power outage. In other words, as shown in this embodiment, there is a technical significance in terms of reducing the time lag in configuring the generated pulse signal so that the HIGH level is dominant.

[0042] If full-wave rectification is performed using the rectifier 72 (corresponding to the "conversion unit") as shown in this embodiment, the period during which the pulse signal generated by the photocoupler 73 is at a HIGH level can be lengthened, that is, the period during which the pulse signal is at a LOW level can be shortened. Also, in a configuration that performs full-wave rectification, the period during which the pulse signal is at a LOW level can be further shortened by setting the threshold value to a voltage close to the lower limit of the converted waveform.

[0043] The CPU 63 of the drive control unit 62 executes power failure response processing based on the input of the power failure detection signal to the digital port. With this configuration, the CPU 63 does not need to perform signal analysis or other processing to detect a power failure, and power failure response processing can be started promptly. In particular, since the CPU 63 has a function of controlling the drive of the robot 15, it is not preferable to allocate large resources to signal analysis. In view of these circumstances, there is technical significance in the configuration in which the power failure detection function is entrusted to the monitoring signal generator 74.

[0044] As described above, in a configuration in which a power failure response process is executed based on an input power failure detection signal, the power failure detection signal needs to be appropriately generated and output. Therefore, as shown in this embodiment, the power failure monitoring circuit 68 is electrically isolated by the photocoupler 73, so that the influence of the input side on the output side can be suppressed. In this way, protecting the power failure signal generator 74 arranged on the output side and suppressing the influence of a failure, etc. is preferable in realizing a configuration in which the power failure detection signal is appropriately generated and output.

[0045] The power failure monitoring circuit 68 (see FIG. 6) shown in this embodiment is superior to the conventional power failure monitoring circuit (see FIG. 5) in the following respects. That is, the various resistors used in the power failure monitoring circuit 68 do not need to be as highly accurate as the resistors used in the conventional power failure monitoring circuit. In addition, there is no need to provide a separate protection circuit in front of the operational amplifier as in the conventional power failure monitoring circuit, and the number of parts can be reduced and the configuration can be simplified in the entire circuit. In general, the configuration related to power failure monitoring can be simplified and space-saving, which can contribute to the miniaturization of the robot controller 61.

[0046] <Other embodiments> The present invention is not limited to the above-described embodiment, and may be implemented as follows. Each of the following configurations may be applied individually to the above-described embodiment, or may be applied in combination with some or all of the following configurations to the above-described embodiment.

[0047] In the above embodiment, the power failure monitoring signal generated by the monitoring signal generator 74 is output to the digital port of the drive control unit 62, and the CPU 63 of the drive control unit 62 executes the power failure response process (steps S102 to S105 in FIG. 3) when the power failure monitoring signal changes from a HIGH signal to a LOW level signal, but this is not limited to the above. The monitoring signal generator 74 may be omitted, and the signal generated by the photocoupler 73 may be input to the digital port of the drive control unit 62, and the CPU 63 of the drive control unit 62 may determine whether the signal is OFF over the above-mentioned determination reference period TX (detect a power failure).

[0048] In the above embodiment, a full-wave rectifier circuit is used as the rectifier 72, but a half-wave rectifier circuit can also be used. However, in such a configuration, the time during which the photocoupler 73 is OFF becomes longer, and as a result, the time required to detect a power outage becomes longer. In other words, the above-mentioned reference period TX becomes longer. Therefore, in order to reduce the time lag until a power outage is detected, it is preferable to use a full-wave rectifier circuit.

[0049] For the photocoupler 73 shown in the above embodiment, the threshold value for generating a pulse signal is set so that the ON time is longer than the OFF time, but this is not limited to this. It is also possible to set the threshold value for generating a pulse signal so that the ON time is shorter than the OFF time. However, in order to reduce the time lag until power outage detection, it is technically meaningful to set the threshold value so that the ON time is longer.

[0050] The photocoupler 73 shown in the above embodiment may be changed to a semiconductor relay in which the light receiving portion 73b, which is an output element, is replaced with a MOSFET.

[0051] The configuration related to power failure monitoring shown in the above embodiment may be applied to robots other than industrial robots used in factories (for example, robots used in restaurants and hospitals). Furthermore, the configuration related to power failure monitoring can also be applied to other industrial machines (for example, machine tools such as NC machine tools and transport machines such as conveyors).

[0052] <Inventions extracted from the above embodiments> The following describes the features of the inventions extracted from the above-mentioned embodiments, while indicating, as necessary, their effects, etc. In the following, for ease of understanding, the corresponding configurations in the above-mentioned embodiments are appropriately indicated in parentheses, but the present invention is not limited to the specific configurations indicated in parentheses.

[0053] <Features Group A> The following feature A group is a background technology that states, "Some robot control systems that control the drive of industrial robots are equipped with an auxiliary power supply in case the power supply from an external power supply is suddenly stopped, i.e., in the event of a power outage. In this type of robot control system, in the event of a power outage, power is supplied from the auxiliary power supply instead of the external power supply, and some are configured to perform stop control for stopping the robot normally while power is being supplied from the auxiliary power supply, and control for saving the position of the robot and the execution status of the control program. For example, in a robot controller described in Patent Document 1, a technology is proposed for controlling the stop of the robot during an operation period using the charged charge of a smoothing capacitor as a power source." When taking the above-mentioned power outage countermeasures, the power consumption of the auxiliary power supply increases as the time lag between the actual occurrence of a power outage and the detection of the occurrence of the power outage and the start of the above-mentioned processing to deal with the power outage increases. In other words, in order to properly function the power outage countermeasures, it becomes necessary to estimate such power consumption in the capacity of the auxiliary power supply, and as a result, the capacity required for the auxiliary power supply increases. Increasing the capacity of the auxiliary power supply leads to an increase in the cost of the power supply module and an increase in the size of the power supply module. Furthermore, an increase in the size of the power supply module can be an obstacle to miniaturization of the object on which the power supply module is mounted (industrial robot or robot controller) and coexistence with other components around the power supply module. This was made in consideration of the above-mentioned problem.

[0054] Feature 1. A robot control system (robot control system 50) for controlling an industrial robot (robot 15), input terminals (input terminals 71a, 71b) to which power is supplied from an external power source which is an AC power source; a pulse signal generating unit (photocoupler 73) that generates a pulse signal that has a first value (e.g., a HIGH level) when an input voltage to the input terminal is above a specific voltage (threshold value) and has a second value (e.g., a LOW level) when the input voltage is below the specific voltage; a power failure response processing execution unit (a function of executing the power failure response processing by the CPU 63) that executes a power failure response processing (processing of steps S102 to S105) when the value of the pulse signal generated by the pulse signal generation unit is the second value over a predetermined period (a judgment reference period TX); A robot control system comprising:

[0055] According to the configuration shown in this feature, a pulse signal is generated from the power (AC) supplied from the external power source. This pulse signal periodically changes between a first value and a second value in a situation where the power supply from the external power source continues. Then, when a power outage occurs, the pulse signal maintains the second value, so that the power outage can be detected from the period during which the pulse signal is at the second value. In this feature, when the value of the pulse signal is at the second value for a predetermined period, it is determined that a power outage has occurred, and a power outage response process is executed. For example, since it is not necessary to take measures such as analyzing an analog signal to detect a power outage, it can contribute to shortening the period required for detection. In addition, since it is not a configuration in which the operating power converted to DC is monitored, it is not necessary to smooth using a capacitor or the like. Therefore, it is possible to avoid delays in power outage detection due to smoothing. For the above reasons, it is possible to shorten the period from when a power outage actually occurs to when a power outage is detected and the period from when a power outage is detected to when a power outage response process is executed. This is preferable in terms of reducing the capacity of the auxiliary power source for use during a power outage mounted in the robot control system, and reducing the cost and suppressing the increase in size of the power source module having the auxiliary power source.

[0056] Feature 2. The pulse signal periodically switches between the first value and the second value while the power supply from the external power source is continuing; 2. The robot control system according to claim 1, wherein the predetermined period is set to be longer than one cycle of the pulse signal.

[0057] For external power supplies, momentary power outages (so-called momentary power outages: power outages with the length of one cycle (20 msec) at 50 / 60 Hz) can occur due to various factors, causing a momentary large drop in voltage. If the robot is stopped every time a momentary power outage occurs, productivity can drop significantly. Therefore, as shown in this feature, by setting the specified period to be longer than the length of one cycle of the pulse signal, it is possible to prevent power outage response processing from being executed in response to a momentary power outage.

[0058] Feature 3. The pulse signal periodically switches between the first value and the second value while the power supply from the external power source is continuing; 3. The robot control system according to claim 1, wherein the pulse signal generating unit generates the pulse signal such that a period during which the pulse signal has the first value is longer than a period during which the pulse signal has the second value.

[0059] In the case where the period during which the generated pulse signal is the second value becomes longer than the period during which the first value becomes dominant, the predetermined period may become longer by taking the period during which the second value becomes dominant. This is not desirable in terms of reducing the time lag in detecting a power outage. In other words, as shown in this feature, there is technical significance in terms of reducing the time lag in configuring the generated pulse signal so that the first value is dominant.

[0060] Feature 4: A robot control system according to any one of Features 1 to 3, further comprising a conversion unit (rectifier 72) for converting a negative voltage portion of the voltage of the supply power to a positive voltage before it is input to the pulse signal generating unit.

[0061] As shown in this feature, if the conversion unit is configured to perform full-wave rectification, the period during which the signal generated by the pulse signal generation unit has a first value can be extended, i.e., the period during which the signal has a second value can be shortened.

[0062] Feature 5. A robot control system according to Feature 4, wherein the specific voltage is a voltage near the lower limit of the voltage waveform converted by the conversion unit.

[0063] In the configuration in which full-wave rectification is performed as described in Feature 4, the period during which the specific voltage is the second value can be further shortened by setting the specific voltage to a voltage near the lower limit of the converted waveform.

[0064] Feature 6. A power failure detection signal generating unit (monitoring signal generator 74) that generates a power failure detection signal when the pulse signal has the first value for the predetermined period; A control unit (drive control unit 62) that controls the drive of the industrial robot; Equipped with The control unit includes the power outage response processing execution unit, A robot control system described in any one of Features 1 to 5, wherein the power outage detection signal generated by the power outage detection signal generating unit is input to a digital port of the control unit (drive control unit 62), and the power outage response processing execution unit executes the power outage response processing based on the power outage detection signal input to the digital port.

[0065] The control unit (power failure response processing execution unit) executes power failure response processing based on the input of a power failure detection signal to the digital port. With this configuration, the control unit does not need to perform signal analysis or other processing to detect a power failure, and power failure response processing can be started promptly. In particular, since the control unit has a function for controlling the drive of the industrial robot, it is not preferable to allocate large resources to signal analysis. In light of these circumstances, there is technical significance in having a configuration that entrusts the detection function to the power failure detection signal generation unit.

[0066] Feature 7. A robot control system according to Feature 6, wherein a power outage monitoring circuit (power outage monitoring circuit 68) including the input terminal and the pulse signal generating unit is electrically separated into an input side and an output side at the pulse signal generating unit.

[0067] As shown in Feature 6, in a configuration in which a power failure response process is executed based on an input power failure detection signal, the power failure detection signal needs to be appropriately generated and output. Therefore, as shown in this feature, by electrically isolating the power failure monitoring circuit in the pulse signal generating unit, it is possible to prevent the influence of the input side from reaching the output side. In this way, protecting the power failure detection signal generating unit and the like arranged on the output side and suppressing the influence of failures and the like is preferable in realizing a configuration in which the power failure detection signal is appropriately generated and output.

[0068] Feature 8. A robot control system according to any one of Features 1 to 7, wherein the pulse signal generating unit is a photocoupler having a light emitting unit (light emitting unit 73a) that emits light in response to power supplied to the input terminal, and a light receiving unit (light receiving unit 73b) to which light from the light emitting unit is irradiated.

[0069] In order to realize the technical ideas shown in Features 1 and 7, it is preferable to configure the pulse signal generating unit using a photocoupler as shown in this feature.

[0070] Feature 9. A power failure monitoring circuit (power failure monitoring circuit 68) applied to a robot control system (robot control system 50) that controls an industrial robot (robot 15), input terminals (input terminals 71a, 71b) to which power is supplied from an external power source which is an AC power source; a pulse signal generating unit (photocoupler 73) that generates a pulse signal that has a first value (e.g., a HIGH level) when an input voltage to the input terminal is above a specific voltage (threshold value) and has a second value (e.g., a LOW level) when the input voltage is below the specific voltage; a power failure detection signal generating unit (monitoring signal generator 74) that generates a power failure detection signal when the value of the pulse signal generated by the pulse signal generating unit is the second value over a predetermined period (a judgment reference period TX) and is capable of outputting the power failure detection signal to a control unit in the robot control system; A power failure monitoring circuit comprising:

[0071] According to the configuration shown in this feature, a pulse signal is generated from the power (AC) supplied from the external power source. This pulse signal periodically changes between a first value and a second value in a situation where the power supply from the external power source continues. Then, when a power outage occurs, the pulse signal maintains the second value, so that the power outage can be detected from the period during which the pulse signal is at the second value. In this feature, a power outage detection signal is generated when the value of the pulse signal is at the second value for a predetermined period. For example, since it is not necessary to analyze an analog signal to detect a power outage, it can contribute to shortening the period required for detection. In addition, since it is not a configuration for monitoring the operating power converted to DC, it is not necessary to smooth using a capacitor or the like. Therefore, it is possible to avoid delays in power outage detection due to smoothing. For the above reasons, it is possible to shorten the period from when a power outage actually occurs to when a power outage is detected. This is preferable in terms of reducing the capacity of the auxiliary power source for use during a power outage mounted in the robot control system, and reducing the cost and suppressing the size of the power source module having the auxiliary power source.

[0072] Feature 10. A power failure monitoring circuit (power failure monitoring circuit 68) applied to a robot control system (robot control system 50) that controls an industrial robot (robot 15), input terminals (input terminals 71a, 71b) to which power is supplied from an external power source which is an AC power source; a pulse signal generating unit (photocoupler 73) that generates a pulse signal that has a first value (e.g., a HIGH level) when an input voltage to the input terminal is above a specific voltage (threshold value) and has a second value (e.g., a LOW level) when the input voltage is below the specific voltage; a conversion unit (rectifier 72) that converts a negative voltage in the voltage of the supply power to a positive voltage before the voltage is input to the pulse signal generation unit; a power failure detection signal generating unit (monitoring signal generator 74) that generates a power failure detection signal when the value of the pulse signal generated by the pulse signal generating unit is the second value over a predetermined period (a judgment reference period TX) and is capable of outputting the power failure detection signal to a control unit in the robot control system; Equipped with The pulse signal generating unit is a photocoupler having a light emitting unit (light emitting unit 73a) that emits light in response to power supplied to the input terminal and a light receiving unit (light receiving unit 73b) to which light from the light emitting unit is irradiated, and the power outage monitoring circuit (power outage monitoring circuit 68) is a power outage monitoring circuit that is electrically separated into an input side and an output side by the pulse signal generating unit.

[0073] This configuration can suitably shorten the period from when a power outage actually occurs until when the power outage is detected. This is advantageous in terms of reducing the capacity of the auxiliary power supply for use in the event of a power outage that is installed in the robot control system, and in terms of reducing the cost and preventing the size of the power supply module that includes the auxiliary power supply. [Explanation of symbols]

[0074] 10...robot system, 15...robot as industrial robot, 21...robot body, 50...robot control system, 61...robot controller, 62...drive control unit, 63...CPU, 65...power supply module, 67...auxiliary power supply, 68...power outage monitoring circuit, 71...input terminal, 72...rectifier, 73...photocoupler, 73a...light emitting unit, 73b...light receiving unit, 74...monitoring signal generator.

Claims

1. A robot control system for controlling an industrial robot, comprising: An input terminal to which power is supplied from an external power source which is an AC power source; a pulse signal generating unit that generates a pulse signal having a first value when an input voltage to the input terminal is higher than a specific voltage and a second value when the input voltage is lower than the specific voltage; a power failure response processing execution unit that executes a power failure response processing when a value of the pulse signal generated by the pulse signal generation unit is the second value for a predetermined period of time; A robot control system comprising:

2. the pulse signal periodically switches between the first value and the second value while the power supply from the external power source is continuing; The robot control system according to claim 1 , wherein the pulse signal generating unit generates the pulse signal so that a period during which the pulse signal has the first value is longer than a period during which the pulse signal has the second value.

3. 2. The robot control system according to claim 1, further comprising a conversion unit that converts a negative voltage in the voltage of the supply power into a positive voltage before the voltage is input to the pulse signal generation unit.

4. A power failure detection signal generating unit that generates a power failure detection signal when the pulse signal has the first value for the predetermined period of time; A control unit that controls the drive of the industrial robot; Equipped with The control unit includes the power outage response processing execution unit, A robot control system as described in any one of claims 1 to 3, wherein the power outage detection signal generated by the power outage detection signal generating unit is input to a digital port of the control unit, and the power outage response processing execution unit executes the power outage response processing based on the power outage detection signal input to the digital port.

5. A power failure monitoring circuit applied to a robot control system for controlling an industrial robot, An input terminal to which power is supplied from an external power source which is an AC power source; a pulse signal generating unit that generates a pulse signal having a first value when an input voltage to the input terminal is higher than a specific voltage and a second value when the input voltage is lower than the specific voltage; a power failure detection signal generating unit that generates a power failure detection signal when a value of the pulse signal generated by the pulse signal generating unit has been the second value for a predetermined period of time, and is capable of outputting the power failure detection signal to a control unit in the robot control system; A power failure monitoring circuit comprising:

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