JPH04176549A - Diagnostic method for failure of production line - Google Patents

Abstract

PURPOSE:To specify a failure part in a production line by comparing the possible motion time of a ladder program element with the actual motion time spent for changing of the ON/OFF states of a confirmation device for confirming the motion of the output device of the ladder program element. CONSTITUTION:In the case of there having been an actuator motion completion the proper block number (i) and step number informed from a ladder program side are read. And from this block number (i) the timer value TSsi, TSei and from a motion step map the execution prediction time tau of the proper motion step, are read, and an elapsed time TS,Y is operated. In the case of it being decided as TSxi-tau>delta0 (delta0 is constant), the motion block belongs to the motion step thereof is marked as failure, and the renewal of the prediction time tauis performed. Also, the motion step marked as under execution is searched, the elapsed time upto the present is calculated, and the proper block is marked as a step hungup failure, in case of Tp-TSsi>delta1 (delta1 is a constant).

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for diagnosing a fault in a production line, and in particular to an improvement in identifying a faulty part in a production line controlled by a sequencer.

[Conventional technology]

In a production line such as an automobile assembly line, a sequence control unit with a built-in computer is provided for the various installed equipment, and the sequence control unit performs sequence control of the operations that each equipment should perform sequentially. It is known to do. When such sequence control is performed, a control program is loaded into a computer built into the sequence control unit, and the sequence control unit performs sequence operation control on each stage of operation control for each of the various equipment installed on the production line. When sequence control is performed on the operation of various equipment installed on a production line, failure diagnosis is performed to monitor the control status and detect failures in each equipment. It is often performed in parallel with control.There are various forms of fault diagnosis related to sequence control.For example, Japanese Patent Laid-Open No. 60
Publication No. 238906 states that the operation mode of the components of the sequence control circuit section when the equipment is operating normally is set in advance as the standard operation mode, and the operation mode of the sequence control circuit section when the equipment is actually operating is set in advance. As one method of fault diagnosis related to sequence control, it has been proposed to sequentially compare the operation mode of a component with the reference operation mode and detect a failure based on the difference. The above failure detection is effective for failures that cause a complete stop, but for minor failures that do not result in a complete stop, for example, equipment that takes a little longer to operate due to aging. For such failures, it is virtually impossible to store all the patterns of such minor failures as standard operating modes, so it is virtually powerless. As a method for detecting such minor faults, a fault diagnosis method called "Trap Method J" has also been proposed. This trap method starts a timer based on the presence of an output on an output device in a sequence control ladder program. , before this timer times out,
A monitoring ladder program is created to check whether a checking device that checks the operation of an output device is working.

[Problem to be solved by the invention]

However, in the trap method described above, it is necessary to create a trap ladder program for each individual ladder program element, which is extremely inefficient. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to propose a production line fault diagnosis method that does not require a fault detection ladder program for each piece of equipment, and that can accurately detect faults. A further object of the present invention is to propose a production line failure diagnosis method that can deal with cases where the operation of equipment changes over time due to changes over time.

[Means and operations for achieving the object] The configuration of the present invention for achieving the above object is such that a production line controlled according to a ladder program created based on a map that describes the operation of individual equipment, pre-storing the expected operating time of each ladder program element corresponding to the operation of said side equipment, and changing the on/off state of a verification device for verifying the operation of the output device of said ladder program element; The present invention is characterized in that a faulty part in the production line is identified by comparing the actual operating time required for the production line with the predicted operating time. According to the fault diagnosis method of the above invention, the predicted time can be mapped, and moreover, a fault can be determined simply by comparing it with the actual operating time. In other words, on the ladder program side,
A conventional timer monitoring circuit is not required. Further, by correcting the expected operating time based on the actual operating time, the expected operating time can be corrected in accordance with the actual operating time, and even if there is a change over time, highly accurate failure diagnosis can be performed. Margin below

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to sequence control/fault diagnosis for an automobile production line will be described below with reference to the accompanying drawings. As shown in FIG. 1, this embodiment system includes a subsystem 106 that automatically generates a ladder program for sequence control and a recovery program, a subsystem 101 that executes the generated ladder program, and a subsystem 101 that detects failures. a subsystem 104 that performs fault diagnosis by identifying a fault location based on a detected fault, and a recovery subsystem 1 that restores the system.
03. FIG. 1 conceptually explains the system of this embodiment. The step ladder program 101 is a program that is loaded into a sequencer or the like to control the equipment 100, and is generated by the automatic generation subsystem 106. The execution of this program 101 is monitored by a monitoring subsystem 104 to detect a failure in the equipment 100. The fault detection subsystem 104 of this embodiment detects three types of faults: r-block hang-up j, 1-step time over, and 1-step hang-up j, and the detection procedures for these will be described later based on the drawings. It will be explained. "Block hang-up j" is a hang-up that occurs during the transition from one motion block (the concept of "motion block" will be explained in conjunction with FIG. 6) to another motion block that follows it. , which could not be detected using conventional techniques. Also,
"Step time over" or "step hang up"
This means that the elapsed time in a certain operating step (the concept of "operating step" will be explained in conjunction with Figure 8) was longer than expected, or a malfunction occurred such as a hang-up at that operating step. be. In order to detect these failures such as "block hang-up,""step time over," and "step hang-up," the fault detection subsystem 104 uses a "block timer counter" and "step timer counter" as described later. ” has been introduced. The failure diagnosis subsystem 105 includes the monitor system 104
The failure is further analyzed to identify the failure location (operation step where the failure occurred). The procedure for this fault diagnosis will also be explained later based on the drawings. The recovery subsystem 103 selects a recovery program 102 that is most appropriate for the operational steps identified by the diagnostic subsystem 105.
is used to start up and restore the system. This recovery program 102 is created by an automatic generation subsystem 106 based on an “operation block map”, “operation step map j”, etc., which will be described later.The explanation of this recovery subsystem and automatic generation of a recovery program will explain the process that would be difficult in the past. It will be understood that automatic creation of a recovery program and accurate automatic recovery are realized in this system. First, the vehicle assembly line to be controlled by the sequence control program 101 will be explained.Next, By explaining the sequence control program automatic generation subsystem 106, we will refer to operation blocks and operation steps, which are important concepts for fault diagnosis in this embodiment.After that, we will explain the fault diagnosis, which is a characteristic part of this embodiment. Detection/Failure Diagnosis/Recovery will be explained. First, an example of a vehicle assembly line to be controlled by a sequence control program to be generated will be described with reference to FIGS. 2 and 3. The vehicle assembly line shown in Figures 2 and 3 exemplarily consists of three stations STI, ST2, ST3.
is received on the pedestal 12, and the position of the pedestal 12 is controlled.
2 and the body 11 is positioned. The docking station ST2 combines the engine 14, the front suspension assembly (not shown), the rear suspension assembly 15, and the body 11 placed at a predetermined position on the pallet 13. The fastening station ST3 fastens and fixes the engine 14 and front suspension assembly 15, which are combined at ST, to the body 11 using screws. Also,
An overhead transfer position 16 for holding and transporting the body 11 is provided between the positioning station STI and the docking station ST2. Docking station ST2 and fastening station ST
A pallet conveyance position 17 for conveying the pallet 13 is provided between the pallet 3 and the pallet 13. The pedestal 12 at the positioning station STI reciprocates along the rail 18. In the positioning station STI, the pedestal 12 is placed in a direction perpendicular to the rail 18 (
By moving the body 11 placed on the pedestal 12 in the vehicle width direction, the positioning means (BF) positions the front part of the body 11 in the vehicle width direction, and also positions the rear part of the body 11 in the vehicle width direction. and positioning means (TL) for positioning the pedestal 12 in the front-back direction by moving it in the direction along the rail 18 (back-and-forth direction). Furthermore, ST
I includes vertical reference bins (FL, FR, RL, R) that position the body 11 relative to the pedestal 12 by engaging with the front left and right parts and the rear left and right parts of the body 11.
R) is provided. Then, by these positioning means and the lifting reference bin, the positioning station ST
A positioning device 19 at I is constructed. That is,
These positioning means and the lifting reference bin are the control targets of the positioning device 19 in the sequence control program. The transfer device 16 includes a guide rail 20 disposed above the positioning station STI and the docking station ST2 with a hook passing between them;
0, and a carrier 21 that moves along 0. An elevating hanger frame 21B is attached to the carrier 21, and the body 11 is supported by the elevating hanger frame 22. As shown in FIG. 4, the lift hanger frame 22 includes a left front support arm 22FL and a right front support arm 22FR, each of which has a pair of front arm clamp parts 2.
2A, and a left rear support arm 22RL and a right rear support arm 22RR (not shown) are each attached via a pair of front arm clamp parts 22B. Each of the left front support arm 22FL and the right front support arm 22FR has a front arm clamp portion 22A.
When the front arm clamp 22A is released from the clamp, it assumes a position extending along the guide rail 20, and when the front arm clamp 22A is clamped, the fourth As shown in the figure, it takes a position extending in a direction perpendicular to the guide rail 20. Similarly, left rear support arm 22R
L. Each of the right rear support arms 22RR also rotates around the rear arm clamp part 22B, and assumes a position extending along the guide 20 when the clamp by the rear arm clamp part 22A is released. When clamping is performed by the rear arm clamp section 22B, the rear arm clamp section 22B assumes a position extending in a direction perpendicular to the guide rail 20. When the body 11 is transferred to the transfer device 16,
As shown by the dashed line in FIG. 2, the transfer device 16 has a left front support arm 22FL and a right front support arm 22F at a position above the front end of the rail 18 (original position).
Each of H extends along the guide rail 20 after being unclamped by the front arm clamp portion 22A. Also,
Left rear support arm 22RL, right rear support arm 22RR
Each of them is unclamped by the rear arm clamp part 22B and extends along the guide rail 20, and then,
The elevating hanger frame 21B is lowered. In this state, the pedestal 12 on which the body 11 is placed is moved along the rail 18 to its front end, and takes a position corresponding to the lifting hanger frame 21B of the transfer device 16 that has been lowered. be made into Each of the left front support arm 22FL and the right front support arm 22FH is
It is rotated to a position extending in a direction perpendicular to the guide rail 20 below the front part of the body 11, and is in a state where it is clamped by the front arm clamp part 22A. Further, each of the left rear support arm 22 RL and the right rear support arm 22 RR is rotated to a position extending in a direction perpendicular to the guide rail 20 below the rear part of the body 11, and the rear arm clamp portion 22B It is in a state where it is clamped. Thereafter, the lifting hanger frame 21B is raised, and as shown in FIG. It is supported by a left rear support arm 22RL and a right rear support arm 22RR. Further, the pallet conveying device 17 includes a pair of guide portions 24L and 24R each provided with a large number of support rollers 23 for receiving the lower surface of the pallet 13, and a pair of guide portions 24L and 24R.
A pair of conveyor rails 25L and 25R extending in parallel to each other on 4H, each having a pallet locking part 26 for locking a pallet 13, and moving along the conveyor rails 25L and 25R, respectively. Pallet transport platform 27L and 2
7R, and a near motor mechanism (not shown) for driving these pallet conveyance tables 27L and 27R. At the docking station ST2, when the front suspension assembly and the rear suspension assembly 15 are respectively assembled, there are a pair of parts that support the struts of the front suspension assembly and the struts 15A of the rear suspension assembly 15, respectively, to take the assembly posture. Left and right front clamp arms 30L
and 30R, and a pair of left and right rear clamp arms 3
1L and 31R are provided. These left and right front clamp arms 30L and 30R are connected to the transport rail 25, respectively.
The left and right rear clamp arms 31L and 31R are attached to the mounting plate parts 32L and 32R so as to be able to move forward and backward in the direction perpendicular to L and 25H, and the left and right rear clamp arms 31L and 31R are attached to the mounting plate part 3, respectively.
It is attached to 3L and 33R so that it can move forward and backward in a direction perpendicular to the transport rails 25L and 25H. mutually opposing tips of left and right front clamp arms 30L and 30R;
The mutually opposing tips of the left and right rear clamp arms 31L and 31R each have an engaging portion that engages with a strut of the front suspension assembly or a strut 15A of the rear suspension assembly 15. The mounting plate portion 32L is mounted on the transport rails 25L and 2 with respect to the fixed base 35L by the arm slide 34L.
It is movable in the direction along 5R. The mounting plate portion 32R is attached to the fixed base 35R by the arm slide 34R.
It is made movable in the direction along the transport rails 25L and 25R. The mounting plate portion 33L is attached to the transport rails 25L and 25H with respect to the fixed base 37L by the arm slide 36L.
It is possible to move along the direction. Furthermore, the mounting plate part 3
3R is movable in the direction along the transport rails 25L and 25H with respect to the fixed base 37R by an arm slide 36R. Therefore, the left and right front clamp arms 3
0L and 30R are movable back and forth, right and left, with their tips engaged with the struts of the front suspension assembly. Further, the left and right rear clamp arms 31L and 31R are movable back and forth and left and right while their tips are engaged with the struts 15A of the rear suspension assembly 15. In addition, these left and right front clamp arms 30L and 30R,
The arm slides 34L and 34R9, the left and right rear clamp arms 31L and 31R1, and the arm slides 36L and 36R constitute a docking device 40. Furthermore, the docking station ST2 includes a pair of slide rails 41L and 41R installed to extend parallel to the transport rails 25L and 25H, respectively, and a movable member that slides along the slide rails 41L and 41R. 42, and a slide device 45 consisting of a motor 43 and the like that drive the movable member 42. The movable member 42 of this slide device 45 includes an engaging means 46 for engaging with a movable engine support member (not shown) provided on the pallet 13, and an engaging means 46 for positioning the pallet 13 at a predetermined position. Two elevating pallet reference pins 47 are provided. Slide device 4
5, a pallet 13 is attached to a body 11 supported by an elevating hanger frame 22 in a transfer device 16.
Engine 14 placed above. When the front suspension assembly and the rear suspension assembly 15 are assembled, the engaging means 46 thereof is moved back and forth while being engaged with the movable engine support member on the pallet 13 positioned by the lifting pallet reference bin 47. The engine 14 is moved back and forth with respect to the body 11 to avoid interference between the body 11 and the engine 14. The fastening station ST3 includes a robot 48A for tightening screws to fasten the engine 14 and front suspension assembly combined to the body 11, and a robot 48A for fastening screws to the body 11 and the rear suspension assembly 15 combined to the body 11. A robot 48B is arranged to perform screw tightening work to fasten the parts. Further, at the fastening station ST3, two
Elevating pallet reference bins 47 are provided. In the vehicle assembly line illustrated in FIGS. 2 to 4, the positioning device 19 at the positioning station STI. Transfer device 16, and docking device 40 and slide device 4 in docking station ST2
5. The pallet transport device 17 and the robots 48A and 48B in the fastening station ST3 are subjected to sequence control by a sequence control unit connected thereto based on a sequence control program generated by the program generation device of this embodiment. That is, these positioning devices 19. The transfer device 16 and the like are regarded as "equipment" to be subjected to sequence control. The assembly operations on the production line shown in FIG. 2, that is, the operations performed by all of the "equipment" subject to sequence control described above, can be broken down into a plurality of "operation blocks."here"
``Action block'' can be defined as ■: a set of multiple unit actions. The most important property of a movement block is: This means that the motion can be completed independently from the motion block of In other words, an action block is related to other action blocks only at the level of the action block.The completion of the action in the other action block is necessary for the action block to be able to start its action. Other operating blocks are
There may be one case, or there may be multiple cases. In other words, the completion of the operation of one action block becomes the start condition for another action block (one or more action blocks) connected to it, or the end of the action of multiple action blocks becomes the start condition. be. Further, according to the above property, there is no need to activate another motion block at an intermediate stage of the motion in one motion block. Further, there is no need to wait for activation from another action block at an intermediate stage of one action block. From the definition of the action block in (1) and (2) above, the following property (2) of the incidental action block can be derived. (2): It is desirable that the action block be the largest among the set of unit actions that satisfy the properties (2) and (3) above. This property of ■ is not absolutely necessary. However, if (2) is satisfied, the number of action blocks that describe the production line is reduced, and the description of the entire process is simplified and becomes very easy to read. If the production line shown in Figs. 2 and 3 is described using operation blocks that satisfy the conditions (1) to (3), the following (
Then, 17 operation blocks of AO-A4 and BO to Bll are obtained. Of the 17 movement blocks above, 12 of BO-B11
Each operation block will be explained. Block BO: An operation block for positioning the pedestal 12 and the body 11- thereon by the positioning device 19. This operation block is called a pedestal positioning block. Block B1: An operation block for making preparations for transferring the body 11 to the transfer position 16. This operation block is called a transfer device preparation block. Block B2: The docking device 40 clamps the struts of the front suspension assembly with the left and right front clamp arms 30L and 30R, and the left and right rear clamp arms 31L. An operation block that prepares for clamping the strut 15A of the rear suspension assembly 15 with 31R. This operation block is called a strut clamp preparation block. Block B3: An operation block in which the body 11 on the pedestal 12, which has been positioned by the positioning device 19, is transferred to the lifting hanger frame 22 in the transfer device 16 and transported. This operation block is called a transfer device receiving block. Block B4 An operational block for preparing the slide device 45 for engaging the engagement means 46 provided on its movable member 42 with the movable engine support member on the pallet 13. This operation block is called a slide device preparation block. Block B5: An operation block in which the positioning device 19 returns the pedestal 12 to its original position. This operation block is called the pedestal original position return block. Block B6: Lifting hanger frame 2 of transfer device 16
Pallet 13
The engine 14 placed above, the struts of the front suspension assembly placed on the pallet 13 and clamped by left and right front clamp arms 30L and 30R, and the struts of the rear suspension assembly 15 clamped by left and right rear clamp arms 31L and 31R. Operation block that combines with 15A. This operating block is called the engine/suspension docking block. Block B7: An operation block in which the transfer device 16 returns to its original position. This operation block is called a transfer device original position return block. Block B8: An operation block in which the docking device 40 returns the left and right front clamp arms 30L, 30R and the left and right rear clamp arms 31L, 31R to their original positions. This operation block is called a clamp arm original position return block. Block B9: The pallet transport device 17 operates the linear motor, and the engine 14. An operation block that transports a pallet 13 on which a body 11 on which a front suspension assembly and a rear suspension assembly 15 are combined is placed to a fastening station ST3. This operation block is called a linear motor propulsion block. Block B10: An operation block in which the robot 48A performs a screw tightening operation for fastening the engine 14 and the front suspension assembly combined to the body 11 to the body 11. This operation block is referred to as a screw tightening first operation block. Block B11: An operation block in which the robot 48B performs screw tightening work for fastening the rear suspension assembly 15 combined with the body 11 to the body 11. This action block is called the second screw tightening block. FIG. 5 shows the relationship between 17 operation blocks, AO to A4 and BO to Bll, in the production line shown in FIGS. 2 to 4. This figure 5 is similar to figures 2~
A programmer who intended to create a sequence control program for the production line shown in FIG. 4 analyzed the operations on this production line and created it. In FIG. 5, two lines are drawn for the block B3 of the transfer device 16 from the operation block BO of the positioning device 19 and the operation block Bl of the transfer device 16. This line is connected to the block B3 by the positioning device 19.
2 and the body 11 thereon (action block BO) are completed, and the preparation for transferring the body 11 at the transfer position 16 (action block Bl) is completed, and then the operation is started. In other words, operation blocks BO and B1
and perform parallel operations. Each of the above-mentioned operation blocks BO to Bll is divided into a plurality of operation steps, each of which involves an output operation. here,
The operation step is required to be accompanied by an output operation. However, since the action steps are constituent elements of action blocks, the action steps within one action block do not perform an output action with respect to the action steps of other action blocks. For example, the pedestal positioning operation block BO is divided into 10 operation steps BO30 to BO39 as follows. BOSO: An operation step for checking various conditions for starting the operation block BO (referred to as a condition confirmation operation step). BO3I: Operation step (BF positioning operation step) in which the pedestal 12 is moved by the positioning means BF and the front part of the body 11 is positioned in the vehicle direction. BO32+ Operation step (BR positioning operation step) in which the pedestal 12 is moved by the positioning means BR and the rear part of the body 11 is positioned in the vehicle width direction. BO33: Operation step (TL positioning operation step) in which the pedestal 12 is moved by the positioning means TL and the body 11 is positioned in the direction along the rail 18 (front-back direction). BO34: Operation step in which the lift reference bin FL engages with the front left side of the body 11 (FL engagement operation step). BO35: Operation step in which the lifting reference bin FR engages with the front right side of the body 11 (FR engagement operation step). BO36: Operation step in which the lifting reference bin RL engages with the rear left side of the body 11 (RL engagement operation step). BO37: Operation step in which the lifting reference bin RR engages with the rear right side of the body 11 (RR engagement operation step). BO38: Operation step (B
F original position return operation step). BOS9: After the positioning means BR positions the rear part of the body 11 in the vehicle width direction, an operation step (B
R original position return operation step). FIG. 8 shows an example of the operational steps of the production line shown in FIG. 2. FIG. 9A represents operating circuit elements for driving, for example, the lifting reference bins, etc. of the production line of FIG. 2. FIG. The input to such an element is an input signal Yo for driving a solenoid as a mechanical element of this element, and this Y. is the output from the sequence ladder program element. Also,
As the output of this element, in order to confirm the operating state of the element, there is an output from the limit switch (output confirmation L/S) to confirm that it has been driven, and to confirm that it has been returned to the original position. There is an output from the limit switch (return confirmation L/S) for this purpose. FIG. 9B is a diagram illustrating the logic of the output drive operation of the element in FIG. 9A. In order for the solenoid to turn on, interlock condition ILC must be satisfied. The interlock conditions ILC - generally include various activation conditions specific to that operating step. FIG. 9C shows an example of a typical operating circuit used when automatically generating the entire sequence. In FIG. 9C, condition MA is closed when this operating circuit is operating in automatic mode (a mode in which the production line operates according to a sequence control program). Condition M3 is closed when this operating circuit is operating in manual mode. M3
is normally closed. Therefore, in normal automatic mode, if interlock conditions ILC and xl are satisfied,
Output Y. is output. On the other hand, ILC. describes the logic of operating conditions in manual mode. In manual mode, contact M is open (so condition X, ILC,
If both are satisfied at the same time, or if conditions X-2XI are satisfied at the same time, then Yo is output. - Generally, X is the logic for killing the manual operation interlock conditioner LC. As is clear from the above, contact conditions MA, Mm
, FIG. 12 shows an example of the embodiment system described in FIG. 1 rewritten from the viewpoint of the hardware configuration. As shown in FIG. 12, this system for sequence control/damage diagnosis/recovery is connected to sequence control target equipment 50 (corresponding to equipment 100 in FIG. 1) and performs sequence operation control thereon. A sequence control section 51 (corresponding to the sequencer 101 in FIG. 1), an automatic generation section 90 (corresponding to the subsystem 106 in FIG. 1), and a failure diagnosis section 52 (subsystems 103, 104, and 104 in FIG.
105) and CRT (cathode ray tube) operation panel section 53
It consists of The sequence control unit 51 includes a program memory 5 in which a sequence operation control ladder program (FIG. 11) is stored.
5, and a computer having a transmitting/receiving interface 54. The failure diagnosis unit 52 detects the path line 61
a central processing unit (CPU) connected through 62.
It has a memory 63, an input/output interface (I10 interface) 64, and a transmission/reception interface 65, and is further provided with a keyboard 66 connected to the I10 interface 64, a CRT 67 for display, and a printer 68. Further, the CRT operation panel section 53 is connected to a CPU 72 through a path line 71.
．． Memory 73. transmission/reception interfaces 74 and 75;
It also has an I10 interface 76, and is further connected to a hard disk device 77 as an auxiliary memory connected to the I10 interface 76, a CRT 78 for display, a keyboard 79 for inputting data and control codes, and a transmission/reception interface 74. A touch panel 80 is provided. touch panel 8
0 is attached to the outer surface of the face plate portion of the CRT 78. Further, the automatic generation section 90 is a section that automatically generates a ladder program for sequence control (FIG. 11) and a ladder program for recovery. Regarding a subsystem that automatically generates a ladder program for sequence control, the present applicant has filed Japanese Patent Application No. 1-253991 (R Sequence Control Program Automatic Creation Device). The transmitting/receiving interface 54 provided in the computer, the transmitting/receiving interface 65 provided in the fault diagnosis section 52, and the transmitting/receiving interface 75 provided in the CRT operation panel section 53 are interconnected. The transmission/reception interface 65 provided in the CRT operation panel section 53, the transmission/reception interface 75 provided on the CRT operation panel section 53, and the interface 96 of the automatic generation section 90 are interconnected. Through 54 and 65, program processing data indicating the operating status of the sequence operation control ladder program and simulation program in the sequence control unit 51 is received and sent to the CPU 6.
2 to obtain a display signal and an output signal based on the program processing data, and supply the display signal to the CRT 67 and the output signal to the printer 68 through the I10 interface 64, respectively. Next, a procedure for automatically creating a sequence control program for sequentially controlling the operation of each facility on the vehicle assembly line as described above will be schematically explained. The data required to automatically generate such a control program are the standard "step ladder pattern", "input/output loop", and the aforementioned "operation block map". This is a "movement step map." The standard step ladder pattern is a database that stores symbols of operation circuits that describe all operations necessary for a production line control program. An example of such a regular pattern is the one shown in FIG. 9C described above. The input/output kamatsubu is a database that describes the input/output relationship of each of the operating circuits that may be used in the production line for boat fishing. An example of this input/output kamatsubu database is shown in Figure 7. The above-mentioned standard step ladder pattern database and input/output step map database are data common to the production line, and are not unique to a particular production line.The unique data is the motion block map data and motion step map data. The operation block map is data that describes each of the above-mentioned operation blocks and also describes the cooperative relationship between these operation blocks. An example of block map data is shown in Fig. 6.A movement step map is unique data that describes the movement steps included in each movement block that is unique to a certain production line.
An example of an operation step map specific to the production line shown in FIG. 8 is shown in FIG. A sequence control program is generated based on these two standard databases and two unique data. First, the standard step ladder pattern database will be explained according to FIG. The OA diagram is a pattern that describes the start and stop of an action block in a typical manner. Figure 10B is the same pattern as described in connection with Figure 9C. FIG. 10C shows one contact condition added to the pattern of FIG. 10B. Next, the input and output will be explained. This input/output guide is a table in which the input/output modes of all equipment used in the production line are described in advance. The input/output hook in Figure 7 is the positioning device 1 in Figure 2.
It is about 9. In this input and output,
“Comment” indicates the contents of the input/output operation. Also"
"Good" is automatically created. Data regarding "Comment", "Operation" and "Original position" are input by operating the keyboard 67. "Output coil device", "Confirmation input contact device" ” and “manual input contact device” are automatically set. For example, the operation circuit called BF (positioning) of Aoz is
The operation type is "output" and the output coil terminal is Yl.
It is. The confirmation input contact name when output is "Xl". Further, the contact name for manual input is "X,". Next, the motion block map will be explained. The data of this map is obtained by analyzing the operation of the target production line and expressing the process of the production line using operation blocks according to the above definition. The operational block map shown in FIG. 5 is a table that represents the operational block chart shown in FIG. 5 when it is obtained as a result of analyzing the production line shown in FIG. In other words, the table (map) of FIG. 6 is approximately equivalent to the chart of FIG. 5. In FIG. 6, "5C-REG" is a 16-bit register, one of which is provided for each of operation blocks BO to Bll. This register indicates which operational step is currently being executed within the corresponding operational block. For example, action block B. And now B0S. If the operation step (see Fig. 8) is being executed, “B, S,” is written in 5CREG of operation block B0.
is stored. "FROM" in the action block map indicates the immediately preceding action block that is the condition for starting the action of the relevant action block. For example, motion block B is motion block B.
0. The completion of B becomes the activation condition. Furthermore, "To" indicates an action block immediately following the action block whose action is started upon completion of the action of the action block. For example, the end of action block B, means the activation of action blocks B, , B,. The "clear condition" is a motion block in which the equipment related to the motion block returns to its original state. Furthermore, "equipment" refers to the sequence control target equipment related to the relevant operation block. The contents of "No" and "5C-REG" are automatically created. On the other hand, “block name”, “FROM”, “To
”, “clear condition” and “equipment” are entered by the programmer by operating the keyboard 67. Next, the operation step map shown in FIG. 8 will be explained. As mentioned above, the operation steps are Describe the details of the specific operations within the block.In other words, the entry/exit switch (Figure 7) does not represent the sequence of operations.However, it also expresses the operation sequence of individual equipment in the operation step map. Figure 8 shows an example of the operation step map of operation block B. In Figure 8, "No" is automatically assigned by the system.
For example, "B oo" for operation block B0. Starting from ``BoS,'' to ``B, S,'', the system generates a ``comment'' each time the programmer inputs a ``comment'' from the keyboard 67. Note that ``Bo. . "B11119" is a motion step that means the preparation of the corresponding motion block, and is placed at the beginning of each motion block in the ladder program.Also, "B 11119" is a motion step that means the completion of the corresponding motion block, and is placed at the beginning of each motion block in the ladder program. It is placed at the end of each motion block.The minimum requirement for generating a motion step map is "comment" information that is input in the order of the step sequence.For example, in step number "B0So", the programmer enters "condition If you enter "Confirm", the number "A" with the comment name "Work present" at the beginning of the input/output Kamatsubu will be displayed.
Read the data of “A o +” of input and output.
Since the confirmation input contact is "Xo" and the manual input contact is "XA", these data are written to the corresponding positions in Fig. 8.The data of "+" is written to the corresponding position in Fig. 8.
"Yo" is the output person given to the first action step of the action block.Subsequently, the programmer selects action step B.
, S, ``'', enter the comment ``BF (positioning)'' and the operation type ``output'', then index the input/output kamatsubu from this title and obtain the data with number ``A 62''.Number `` The data for ``802'' is ``Yl'' for the ``output coil,''``Xl'' for the ``confirmation input contact,'' and ``XIl'' for the ``manual input contact.'' Write the corresponding data. In this way, the motion step map (Figure 8) writes the corresponding data into the input/output map (Figure 7) based on the "comment" and "motion type" entered by the programmer. Search and create. Further, such a motion step map is created for each motion block. In the operation step map shown in FIG. 8, the data on the side of -Koseki is the predicted operation time of each operation step. This data is important data for detecting and determining the above-mentioned ``step time over'' and ``step hang-up 1 error.'' Figure 11 shows the sequence ladder program for block B0 generated in this way. The structure of the ladder program can be better understood by comparing the ladder program in Fig. 11 with the operation step map in Fig. 8.For example, in operation step B.So, the automatic operation mode in which contact MA is closed In this case, contact device
Since 0 is closed, output Y1 is output. When Y is output, the confirmation input contact Xo is closed in BoSI, so ¥1 is output. The above is a description of the automatic generation of the sequence control ladder program in the system of this embodiment, and through this explanation, the mutual operations between the respective operation blocks will be understood using the operation block map (FIG. 6). Also, the operation step map and the input/output map (FIG. 7) will help you understand how efficiently the control program can be automatically generated. Below, we have explained the automatic generation of the ladder program in the system of this embodiment. Also, in the process, I was able to understand what a motion block map and motion steps are. FIG. 13 explains the relationship between the control programs in the fault detection/fault diagnosis subsystems 104 and 105 in FIG. 1, and the relationship between them and the step ladder program 200 (101 in FIG. 1). . Sequence control, monitoring, and failure diagnosis of this system will be explained using the same figure. While the automatic program generation described above is a program that operates separately and independently from the sequence control and fault diagnosis, as will become clear later, the sequence control program and the fault detection/diagnosis program are closely related to each other. Operate. In FIG. 13, the step ladder program 200 is the ladder program shown in FIG.
As explained in connection with FIG. 1, specific operations of individual actuators in individual operation steps are described. The map control program 201 also includes an operation block map (Fig. 6) and an operation step map (Fig. 6).
The operation of the equipment executed by the ladder program 200 is monitored while referring to FIG. Details of this map control program 201 are shown in FIG. 16A. Further, the operation monitoring program 202 detects the occurrence of a failure while monitoring the exchange between the map control program 201 and the ladder program 200.
Shown in Figure B. Further, the failure diagnosis program 203 performs a failure diagnosis when notified by the monitoring program 202 that a failure has occurred. The actuator (that is, the operation step) in which this failure occurred is determined by the monitoring program 202 and the map control program 2.
This can be known by the diagnostic program 203 examining the contents of a step counter, which will be described later, and which is recorded by 01. The specific device or contact within the actuator can be detected by the diagnostic program 203 based on the data of the input and output ports (FIG. 7). In order to understand the failure diagnosis system, the above-mentioned 5C-REG (abbreviated as C8) set for each operation block is required.
It is necessary to understand the following. FIG. 14 shows the above CS register and time register (TS,...) provided in a certain operation block i (BL,).
TS, ) and the block time register TB. The cs register C81 stores the number of the last completed operation step in block i. Further, the step time register TS stores the time when the last executed or currently executed operation step was started. TS, , stores the time at which the last action step that was executed ended. Further, the block time register TB is zero until the block becomes activated. When activation becomes possible, the time when activation becomes possible is stored in TB. FIG. 15 shows how each of the above registers is set in each block. At the point when the execution of a certain operation step is finished, T S
,,=T S ,,-T S ,,...
...(1) is the time required to execute the operation step. As mentioned above, counter C8, stores the number of the last operation step that block i finished executing (actually, it indicates the number of the next operation step after that operation step), so from the contents of C8, , the time TSO required to execute the last completed operational step can be calculated. In the fault diagnosis system of this embodiment, by comparing this TS, , with the standard time required to execute each operation step stored in the operation step map shown in FIG. 8, TS, , -τ> If δ0...(2), it is determined that there was a failure (r step time over J described above) in the execution of the operation step. Here δ. is a constant. In addition, in this fault diagnosis system, the operation steps that have not yet been executed are periodically scanned, and the elapsed time T p T S s l up to the present time is determined as Tp −TSm, > δ
1 (3), it is determined that the operation step is in a loop or hangs up. Here, T is the current time, and δ1 is a constant. δ1 is typically the maximum time required to perform an operational step on the production line, with some tolerance. Such a failure is a "step hang-up." Block hang-up "Block hang-up" will be explained using FIG. 15 and FIGS. 19A to 19E. As shown in FIG. 15 or 5, there are a plurality of blocks that operate in parallel with each other. Considering such a plurality of blocks as a group, one group (first
In the example in Figure 5, all the step operations of the group (BLI forms one group) are completed, and the other group following that group (in the example in Figure 15, the GRI consisting of BL2, BL3, and BL4) is executed. It is necessary to monitor the elapsed time until the The block time register TB mentioned above is
This is the elapsed time until the block group is activated. By monitoring the measurement operation time for each group and comparing it with the reference time, we can detect abnormalities in each group.
In other words, it is now possible to diagnose a fault that occurs during the transition from one block to another. Such a failure is r-block hang-up 1. In the system of this embodiment, when a block hang-up occurs, further steps are performed to identify the operation step that caused the block hang-up. A method for identifying the operation step that caused "r block hang-up" will be explained using FIGS. 19A to 19E. These FIGS. 19A to 19E are simplified versions of the production line shown in FIG. 5 in order to facilitate the explanation of "r-block hang-up." In FIG. 19A, the production line simply consists of four operating blocks. The motion block map for these motion blocks is shown in a simplified manner as shown in FIG. 19B. In FIG. 19B, the time required from block 1 to block 2 to be activated is expressed as "12," the time required from block 1 to block 3 to be activated is expressed as r13, etc. These transition times are expressed as " This is because block 4 can be set in advance.For example, block 4 can be configured in parallel with block 2,
It is activated upon completion of step 3. As explained in connection with FIG. 15, the block time register TB is zero until the block is ready to start. Then, when it becomes possible to start, the time is stored. Therefore, if the value of register TB is not zero (and the elapsed time up to the present time is sufficiently larger than the above value, it can be determined that a block hang-up has occurred. Therefore, block 2.
If block 4 is not activated even after time r 24.1734 has elapsed since the end of block 3, the failure is recognized as block hang-up. When a block hangup is detected because block 4 is not activated, the operational step that caused it must be in either block 2 or 3. FIG. 19C shows the action step map of action block 2, and FIG. 19D shows the action step map of block 3. According to FIG. 19C, four operation steps are set in block 2, and the output at each step is Yl, Y-,...
・Y4, and the confirmation switches of those output actuators are X, , X, . . . x4. Also, the 19th D
According to the figure, three operation steps are set in block 3, and the outputs at each step are Ys, Y,...
Y, and the confirmation switches of their output actuators are X,,X,,X,. The states of the confirmation switches X1 to X are as follows at the time of ending blocks 2 and 3.
Each block is unique and can be known in advance. The activation condition map of FIG. 19E shows the conditions for activating each of the four operation blocks shown in the example of FIG. 19A, that is, the state logic of the operation confirmation switch. Regarding block 4 in the figure, in block 2, outputs ¥1 to Y4 are turned on, and confirmation switches X to X4 are turned on. Also, block 3
Then, outputs Y4 to Y are turned on, and confirmation switch X4 is turned on.
7 to X7 are turned on. Therefore, when block 4 is activated normally, X+ *X2 * ... *X. Must be. Blocks 2 and 3 are activated by the end of block 1. Therefore, the activation condition for blocks 2 and 3 is the logical product of the confirmation switch states of all the operation steps of block 1. In FIG. 19E, (N> means that the confirmation switch is in the state of confirming that output Y is in the "out" state, and <I> means that the confirmation switch is in the state of confirming that output Y is in the "return" state.
It means to be in a state to confirm that it is in a state. In this way, if the activation condition of each operation block is programmed with the logical product of the device states that confirm the outputs of all operation steps of the block preceding the block, the activation of the operation block will be as follows: It is not performed unless it is confirmed that all the operation steps of the previous operation block have completed normally. In other words, if the activation conditions are not satisfied, the aforementioned block hang-up occurs and is correctly detected as a failure. Moreover, once the block in which a failure has been detected is recognized, by comparing the startup condition map and the actual state of the confirmation switch, it is possible to determine which switch is abnormal, and whether the input/output switch (Figure 7) is operating correctly. By referring to the step map (FIG. 8), it is possible to quickly find out which output actuator in which operation step is at fault. In sequence control on a production line, from experience, the actuator of the operation step is not in the "out" state, but in the "out" state.
If the machine stops in a state where it is not in the "return" state, or if
In some cases, it may indicate both the state and the [Return] state. One of the reasons for this is that the heavy actuator falls into a "halfway" state due to bounce, neither in the "out" state (nor in the "return" state). The situation is that the sequence control appears to be proceeding normally, but the operation step (of another operation block) that is supposed to be activated due to the status of the defective confirmation switch is not activated for a long time, resulting in a failure. However, the stopping point is,
There is a high possibility that this is an operation step that is far away from the operation step where the failure actually occurred. However, according to the block hang-up detection method of this embodiment, as described above, the activation condition of each operation block is a logical product of the logical states that all check devices of the previous block should be in, as shown in FIG. 19E. is set, so even if you fall into the above-mentioned halfway switch state at the operation step of one operation block and cannot recognize it as a failure at that operation step, that operation block will end and the next one will continue. This can be seen as a block hangup when a motion block is activated. In other words, the operational step in which the failure occurred and the operational step in which the failure was recognized are not too far apart in time and space, which not only makes failure diagnosis more accurate, but also speeds up recovery. It has the effect of becoming. When a failure is detected due to step time over, step hang-up, block hang-up, etc. as described above, the faulty actuator is identified from the operation step map (FIG. 8) by identifying the failure step. This is because, as shown in FIG. 8, one operation step corresponds to one actuator. Here, from the faulty actuator, the state in which this actuator is stopped, that is, the LS (two limit switches L for output and return) that define the operation of this actuator.
It is necessary to know what state S) is in. The input/output switch in FIG. 7 and the operation step map in FIG. 8 are used to know the state of this LS. In the operation step map of FIG. 8, an actuator identification number column is provided. This identification number is a number (eg, AOI) that identifies the actuator used in the corresponding step (eg, BoSo). This identification number is the number of each individual item in the inlet and outlet. The input/output switch in FIG. 7 not only indicates the operation type and contact name of each actuator, but also describes the relationship between the contact indicating the out state and the contact indicating the return state. Since the actuator performs reciprocating motion, one actuator always has an output state and a return state. In the input/output kamatsubu in Figure 7, the "correspondence" is as follows:
The bear relationship is described. For example, "AO3" is written in the correspondence column for the actuator BF (this actuator is identified by the number AO2). In other words, number A indicates when the BF actuator is in the extended state.
The return state specified by O2 and corresponding to this exit state is:
It shows that it is at number AO3. Therefore, once the fault diagnosis system has obtained the fault block number and fault operation step number, it knows the identification number of the faulty actuator from the action step map, and from this number, what kind of LS is assigned to this faulty actuator?
You can check whether it is set. Then, if you can know which LS is installed,
By reading out the state of S and displaying it, for example,
The failure status can be communicated to the operator. The input/output switch in FIG. 7 is independent of the motion step map (FIG. 8) that describes the actual motion sequence and the ladder program (FIG. 11). That is, even if the production line is changed and the operation step map (FIG. 8) or ladder program (FIG. 11) is modified, there is no need to modify the input and output ports. That is, the user is freed from the effort of modifying the fault diagnosis program every time the production line is changed. The above-mentioned standard execution time is defined by, for example, the average value TS□ of the measured operation time for a predetermined number of cycles during normal operation and the standard deviation value σ, for example, y=Tsx++ 3a..."
(4) is preferably defined. More preferably, the data τ is updated every cycle. Because,
This is because the operating characteristics of the actuator change over time. Furthermore, it is desirable to update the time r (see the operation block map in FIG. 6) used for detecting block hang-up based on the actual time required, taking into account changes over time. 1 Pre-Stop I Next, the control operation in the system of this embodiment will be explained according to FIGS. 16A to 16C. FIG. 16A shows a control procedure of the map control program 201 which monitors the operation of each actuator on the production line in accordance with the operation block map and the operation step map in the ladder program 200. When this program is started, in step S2, initialization is performed and the first block group that can be started is detected. This group has 1
It may contain one block or it may contain multiple blocks. In step S4, the existence of a newly enabled block is checked. The purpose of step S4 is mainly to check whether there is any executable action block following the completion of all the steps of one action block. If such a block exists (if it is started from step S2, there must be an executable action block), then in step S6,
Detect that block number. Let such block number be i
Of course, this number can include multiple numbers. This is because there are cases where it can be executed by a group. In step S8, the action step map of such an action block is read, and in step SIO, the action block is marked as being executed. In step S12, it is checked whether there are any executable action steps. The operation step becomes executable when the operation of the operation step indicated in the CS register is completed, and is performed at step 554 (FIG. 16B) of the monitoring program 202. If there is an executable action step in the action block, the current time is written in the timer register TS of the action block i as the start time in step S32. The operation in step S32 is performed as long as there are executable operation steps. In practice, if there are multiple action blocks within a group, one action step will be performed in each of the action blocks. Once all executable action steps have been activated, step S1 continues until the action of any action step is completed.
If the determination in step 2 is NO, the process proceeds to step S14 and waits for the completion of execution of any of the operation steps. When an end signal is transmitted from the ladder program to the sequence control program indicating that the execution of any of the operation steps has ended, the process advances from step S14 to step 316. Here, the completed operation block number i and operation step number (see FIG. 13) are read. The action block including the completed action step can be specified by this i. In step 818, the end time is written to the timer register TS1 of the operation block i, and in step S20, the CS register is incremented by one to indicate the next operation step to be executed. If such an operation is performed, the CS register of the corresponding block will be updated and T S -1 will also be updated in order from the operation step where the actuator operation is completed. On the other hand, the monitoring program 202 monitors the step end signal from the ladder program 200 in step S40 of FIG. 16B. If the actuator operation ends in any ladder element, step S42
Then, read the block number i and step number notified from the ladder program. And step S
At step 44, the timer values TS, , TS, of the block are read from the block number i, as well as the predicted execution time τ of the operation step from the operation step map, and the elapsed time TS is calculated according to equation (1). . Then, in step 346, it is determined whether the time TS required for execution was abnormally long. If the determination in step S46 is OK, step S52
In step S54, the content of the timer register of the operation block is cleared, and in step S54, the operation step currently indicated in register C8 is marked as executable. The operation step indicated by C81 is the next operation step that has been completed, as updated in step S20. When an action step of a certain action block is marked as executable, YES is determined in step SL2 of FIG. 16A of the sequence control program, and the next action step is executed. When the operation steps are executed one after another in this way, in step S22 for a certain operation block, when the contents of the CS register exceed the final step number, that is,
There is a time when all processing of the operation block is completed (in this case, in step S24, the block is marked as finished, and in step S26, a timer is set for the block to be activated next to the current block). Write the current time to TB, , where TB,J is the block j that should be activated next to block i after block i has finished.
This is a timer to clearly indicate the existence of the 19th
This corresponds to U lx etc. in Figure B. In addition, time register TB
is cleared in step S30 when the first action step of the action block to be started next is started. Returning from step S26 to step SS4, a new executable action block is searched for. For example, in the example of Figure 5, B
When the processing of O is completed and the process returns to step S4, if the processing of B1 has not yet been completed, B3 is not marked as executable. Next, returning to step S46 in FIG. 16B, the procedure for discovering a step time-over failure will be described. In step 346, TS. −te〉δ. If it is determined that the time taken to execute the operation step is abnormally long, step S48 is executed.
Then, the operation block to which the operation step belongs is marked as a failure, and at step S49, the estimated time is updated. The details of this update process are shown in FIG. 16D, and the difference between the time T8□ actually required to process the motion step and the expected time τ is small, that is, T8□−τ □ ε (( 1) If the time required is slightly longer than before, it is assumed that this is due to aging of the equipment, and
In step 5102, past TXI and current T
From XI, calculate and update the value for the next time. Such updates enable accurate failure detection that also takes secular changes into account. In the control procedure of FIG. 16B, the diagnostic program (FIG. 16C) is started in step S50, and then step S
Return to 40. The reason why the process returns to step S40 is to detect a failure also in the operation steps of other operation blocks. Furthermore, the reason why the execution of the sequence control program (Figure 16A) is not stopped after detecting a failure is because even if one operation block is stopped, there are other operation blocks that should run in parallel, so the operation of that operation block is stopped. This is because you must not do so. The reason why it is not necessary to stop other motion blocks is because the motion blocks are originally defined on the condition that they operate independently of other motion blocks. Step 356 and subsequent steps are procedures for detecting block hangup or step hangup. This section explains what to do when the ladder program hangs up at a certain operation step. In such a case, no end signal is generated. Therefore, the process advances from step S40 to step S56. In step S56, the passage of a certain period of time is checked. This is the current point in time (time T
, ) exceeds a certain value. In other words, the presence or absence of block hang-up or step hang-up is checked at regular intervals. In step S58, an operation step marked as being executed is searched for. This means that the contents of each CS register of an operation block marked as being executed points to a specific operation step, and the TS□
Although the start time has been written in TS, , has not been updated yet. In step S60, the elapsed time Tp-TS up to the present time is calculated, and in step S62
Then, according to equation (3), T p T S s + > δ, -...
...Determine (3). If the determination is YES, the process proceeds to step S64 and the block is marked as a step hang-up failure. A case where it is determined in step S58 that there is no operation step being executed will be described. In this case, step S
At 70, a search is made for a block j whose block time register TB, . . . has a non-zero value. As described above in relation to step S26, if TB is not zero, this indicates that even after block i has ended, the subsequent block (block j) has not yet been activated. In step S72, the Difference between the elapsed time during which the operation step remains unactivated and the expected time "1," (T, -TB, ,)
-r,. Calculate. If the difference is greater than the constant 62, it is determined in step 376 that the block is hung up. In step 578, the fault diagnosis program (16th
(Figure C). The failure diagnosis program 203 will be explained according to FIG. 16C. This fault diagnosis program has slightly different processing depending on whether the fault is a block hang-up, a step time over, or a step hang-up. This is because if step time over or step hangup is detected, the faulty operation step can be directly known, whereas in the case of block hangup, it is necessary to trace through the faulty action steps. In the case of a step time-over or step hang-up failure, a block marked as failure is searched for in step S82. This mark was made in step S48 or step S66. Step S
At 72, the contents of the CS register of the detected block are read to identify the failed operational step. Step S7
In step 4, the identification number of the failed actuator is determined from the operation step map. In step S76, the incoming and outgoing kamatsubu (Fig. 7) is searched based on this identification number, and step S76 is performed.
At 78, the outgoing and returning LS numbers of the actuator having this identification number are determined. In step S80, these things were known. The operation block number, operation step number, actuator number, and LS number where the failure occurred are displayed to prompt the operator to take corrective action. A case where block hang-up is detected in step S80 will be described. In this case, in step S96,
The activation condition map (FIG. 19E) corresponding to the block number in which block hang-up has been detected is read. In step 398, the logical states of the confirmation switches written on the map are compared with the actual states of those confirmation switches to find a confirmation switch that does not match. Once this mismatched switch device has been identified, next, in step 5100, the block map (FIG. 6) is searched for the parent block of the block in which the hang-up has been detected. Step 51
In step 02, the operation step that uses the mismatched switch is identified from the operation step map (Fig. 8) of the detected parent block, and from now on, in step 5102, the actuator number and L/S number of this operation step are identified. The process then proceeds to step S92. In step S92, the fault locations searched in the manner of 0 or more are highlighted in a predetermined color on the monitor screen of the display device 8. Then, the worker performs restoration work at the failed location. The detection of "r-step time over" and "r-step hang-up" described above is basically performed by a program independent of the step ladder program 203. This has the following effects. That is, it is no longer necessary to provide a so-called "trap circuit" for detecting the above-mentioned failure in the step ladder program. In FIG. 20(b), Ml is an output due to satisfaction of interlock condition ILC, and when My is output, actuator output Y is output. Conventionally, as shown in FIG. 20(b), a timer circuit T is provided which is activated when the switch M is closed.
If the switch XL3, which checks the output Y, is not opened before this timer times out, a failure (ALM on) is determined. However, according to this embodiment, such a timer circuit is no longer necessary, and as shown in FIG. 20(a),
This means that it is only necessary to create step ladder programs necessary for original production sequence control. The above are the fault detection/fault diagnosis methods provided in the system of this embodiment. Next, a method for restarting the entire system from a fault detected in this way (failure recovery subsystem 103 in FIG. 1) will be described. As explained in connection with FIG. 1, this recovery subsystem 103 includes a previously generated recovery program 102.
Restoration will be carried out based on the following. Therefore, automatic generation of a recovery program in this system will be explained. FIG. 21 explains the operating principle of this recovery subsystem. During the execution of a certain block B, , its operation step B
In the past, if there was a failure in I, S, BnS was manually operated. -BllS6... and proceeded with the steps. However, with this conventional method, not only is the recovery process not automated, but the manual step progression often gets stuck in the middle. In this recovery subsystem, as shown in FIG. 21, the operation is reversed from the failed operation step B, , Ss, to the beginning B, S of this block B, and the operation step B at the beginning is returned. This is to restart from Sl. In other words, the backward ladder program (
If the ladder program during normal sequence control is the one shown in FIG. 11, the RRP (referred to as RRP) will be as shown in FIG. 22. As can be seen by comparing Figures 11 and 22, this recovery ladder program RR
P is such that the operation confirmation switch of output Y in a certain operation step in FIG. 11 is set as a manual interlock condition for the preceding operation step. I will explain in detail. In the step ladder program shown in FIG. 11, which is a ladder program of the action step map shown in FIG. This becomes the output Y2 in S2. The operation of this output Y2 is checked by a switch X2. On the other hand, in RR of FIG. 22, the confirmation switch X of output Y3
3 is closed, output Y2 is output manually, and when confirmation switch X2 of this Y2 is closed, RR,
At this point, an output Y1 is output. In this way, in the recovery ladder program RRP, the reverse control explained in FIG. It has been realized. FIG. 17 shows the above-mentioned backward ladder program RRP.
13 is a flowchart of a program for automatically generating . This program is stored in the subsystem 106 in FIG. 1 or in the automatic generation unit 90 in FIG. 13. When this automatic generation program is started, in step 5150 of FIG. 17, the operator is prompted to specify the block number n to be generated. In step 5152,
Read the operation step map corresponding to that block number. In step 5154, m, which corresponds to the step number of the sequence control ladder program SRP, is initialized to the maximum value. In step 8156, k corresponding to the step number of the recovery program RRP is initialized to "1". In step 5158, from the operation step map, the output Y of SRP, B, , S=, and the output Y of RRP,
Assign to k. In step 8160, the confirmation switch X of the output Y1 of B, , S, is assigned to the interlock condition of RRPk. In step 8162, k is incremented, and in step 8164, m is decremented by one. The above operation is performed in step 8166, m=0
Repeat until . In this way, the recovery program 102 is automatically generated and stored in the hardware disk 77 without being activated until the recovery switch (not shown) is pressed by the operator. FIG. 18 shows the control procedure of the control program for the recovery subsystem that is activated when the recovery switch is pressed by the operator. When a failure occurs, if the failure is step time over or step hang-up, the failure operation step in the block where the failure occurred is indicated by the CS register and stopped according to the control procedure of FIG. 16C. The other blocks are waiting for the failed plot to restart. If the block hangs up, the system waits for restart with the failed operation step identified according to the control procedure shown in FIG. 16C. When the switch is pressed in FIG. 18, in step 5182, the faulty block and faulty action step identified as described above are input. Step 51
At step 84, the recovery program corresponding to the failed block is read from the disk 77, and the program is loaded into the sequencer. In step 8186, this recovery ladder program RRP is started from step number k corresponding to the failed operation step known in step 8182. In step 5188, the end of this recovery program is waited for, and in step 5190, the step ladder program SRP is reloaded into the sequencer, and in step 5192, this ladder program is restarted. As explained above, according to the failure detection/diagnosis/recovery system of this embodiment, ■ easy and accurate detection of two-step time over, step hang-up, and block hang-up; It is possible to detect failures. That is, the step time over detection of the system of this embodiment,
With step hang-up detection, there is no need to incorporate a failure detection circuit into the ladder program as in the past.
Simplifications have been made. In particular, in step time over detection, the standard expected time τ
is updated based on actual data, so its detection accuracy is ensured. Furthermore, by incorporating the block activation condition into the activation condition of each block, a failure state such as a confirmation switch being turned on in a halfway state can be recognized as a block hang-up state. By this recognition, such a fault condition can be detected as a block hang-up at an early stage before the number of operation steps has progressed, and as a result, more accurate fault diagnosis can be performed. By setting the confirmation switch as an interlock condition for the recovery ladder program RRP, a recovery program can be automatically generated very easily using only the operation step map.In addition, by starting this recovery program, By taking the method of returning the blocked block to its initial state and then skipping the restart,
Recovery will be more certain. The present invention can be modified in various ways without departing from the spirit thereof. For example, in the above embodiment, the present invention was applied to an automobile production line, but of course the present invention is not limited to such an application field, and can be applied at least as long as sequence control is performed. It is possible. Blank space below [Effects of the Invention] As explained above, the fault detection method of the present invention is such that, in a production line that is controlled according to a ladder program created based on a map that describes the operation of each piece of equipment, The expected operating time of each ladder program element corresponding to the operation of the equipment is stored in advance, and the actual time required for the on/off state of the verification device to confirm the operation of the output device of said ladder program element is stored in advance. The present invention is characterized in that a faulty part in the production line is identified by comparing the operating time with the predicted operating time. According to the fault diagnosis method of the above invention, the predicted time can be mapped, and moreover, a fault can be determined simply by comparing it with the actual operating time. In other words, on the ladder program side,
A conventional timer monitoring circuit is not required. Further, by correcting the expected operating time based on the actual operating time, the expected operating time can be corrected in accordance with the actual operating time, and even if there is a change over time, highly accurate failure diagnosis can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the functions provided in a preferred embodiment of the present invention, and Figs. 2 to 4 show the configuration of an assembly line for automobiles when the present invention is applied to the assembly line. FIG. 5 is a diagram explaining the connection relationship between the operation blocks when the assembly line is disassembled into operation blocks. FIG. 6 is a diagram explaining the structure of the operation block map. Figure 8 is a diagram explaining the structure of the input/output switch, Figure 8 is a diagram explaining the structure of the operation step map, Figure 9A is a diagram explaining the notation when equipment is symbolized by an actuator, and Figure 9B is a diagram explaining the structure of a single actuator. A diagram explaining the logic of the actuator, FIG. 9C is a diagram showing one example of a step ladder pattern, FIGS. 10A to 10C are diagrams showing other examples of step ladder patterns, and FIG. 11 is similar to FIG. FIG. 12 is a block diagram illustrating the hardware configuration of the example system. FIG. 13 is a diagram showing the ladder program, sequence control program, and monitoring in the example system. Figures 14 and 15 are diagrams explaining the relationship between the program and the fault diagnosis program. Figures 14 and 15 are diagrams explaining the fault detection method. Figures 16A to 16C are the sequence control program, monitoring program, and failure diagnosis program, respectively. FIG. 16D is a flowchart of a control procedure for matching the expected execution time of an operation step with actual data. FIG. 17 is a flowchart of a control program for automatically generating a recovery ladder program. 18 is a flowchart showing the procedure of a control program for executing an automatically generated recovery ladder program, and FIGS. 19A to 19E are diagrams explaining the principle for detecting block hang-up. , FIG. 20 shows a comparison between the system of the present embodiment and the conventional system, which shows the advantage of detecting a failure in an operation step by setting a reference time and comparing this reference time with the elapsed time of the operation step. FIG. 21 is a diagram explaining the principle of the recovery procedure in this embodiment, and FIG. 22 is a diagram showing an example of a beam recovery ladder program.

Claims (2)

[Claims] (1) In a production line that is controlled according to a ladder program created based on a map that describes the operation of each piece of equipment, the map includes the expected operating time of each ladder program element corresponding to the operation of each piece of equipment. A check for checking the operation of the output device of the ladder program element by comparing the actual operation time required for the on/off state of the output device to change with the expected operation time. A production line failure diagnosis method characterized by identifying a failure part. (2) The production line failure diagnosis method according to claim 1, wherein when the expected operating time is different from the actual operating time, the estimated operating time is corrected based on the actual operating time.