Industrial robot system

Abstract: An industrial robot system comprises a control unit including programs for operating an industrial robot and a peripheral device of the industrial robot according to the programs; a memory (6) for storing the steps of the programs which are effected when the industrial robot and peripheral device are stopped unintentionally; a detector (7) for detecting the conditions of the industrial robot and peripheral device when the industrial robot and peripheral device are stopped unintentionally; and a restarter (9) for starting the industrial robot and peripheral device again when the contents of the memory coincide with the conditions detected by the detectors.

Description: This invention relates to an industrial robot system, according to the preamble of claim 1. (Prior Art) As disclosed by Japanese Patent Application (OPI) No. 88301/1986, an industrial robot system is available which is provided with earthquake control means operating on an earthquake detector at the occurrence of an earthquake. In the industrial robot system, an earthquake control operation is carried out to stop the operation of the industrial robot or retract it from line when an earthquake occurs. The above-described conventional industrial robot system suffers from the following problem: When the industrial robot system is stopped unintentionally, the actual condition of the industrial robot or its peripheral materials such as work materials is often deviated from that required by the operating program for instance because it is manually moved after the unintentional stop. Hence, when the industrial robot system is started again, troubles may occur, for instance the industrial robot may perform unexpected operations to damage the peripheral equipment. From the JP-A-57 168 306 an industrial robot system having the features according to the preamble of claim 1 is known. In particular, according to this document, after a discontinuation the robot is manually shifted to the position where repair and inspection are easily carried out. Then a command for restarting is given, and the robot is reset. When the robot returns to a data position corresponding to stored position data the operation is automatically started. From JP-A-60 159 904 a plant restarting system is known which comprises a sequency holding the release to the equipment only which can be restarted. In order to check whether restarting is possible, a plurality of sequencers is successively selected and compared with information stored in advance in a computer. The EP-A-0 171 435 discloses a numerical control method for controlling a machine tool or the like, and programmable controller unit. In this method, a NC unit executes a machining program from the start thereof to a predetermined program block from which the operation may be restarted. SUMMARY OF THE INVENTION Accordingly, an object of this invention is to eliminate the above-described difficulty accompanying a conventional industrial robot system. More specifically, an object of the invention is to provide an industrial robot system which, when it is stopped unintentionally and then started again, will operate correctly. The foregoing object of the invention has been achieved by the provision of an industrial robot system of the initially defined type having the characterizing features of claim 1. In the case where, in the industrial robot system thus organized, the industrial robot and its peripheral device are stopped unintentionally, the restarter is operated when the outputs of the memory means and the detector means coincide with each other. Furthermore, the program control means operates to search for the steps of the programs which correspond to the outputs of the detector means. When it is determined that the system cannot be restarted, the system is left as it is, with the annunciator energized. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory diagram outlining the entire arrangement of one example of an industrial robot system according to this invention; Fig. 2 is a plan view of the industrial robot system shown in Fig. 1; Fig. 3 is a block diagram showing an electrical connection in the industrial robot system in Fig. 1; and Fig. 4 is a flow chart for a description of the operation of the industrial robot system shown in Fig. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figs. 1 through 4 shows one embodiment of this invention, an industrial robot system. In these figures, reference numeral 1 designates an industrial robot with a control unit including a program; 2, a first peripheral device comprising a pallet supplying conveyor installed near the industrial robot 1 and having a control unit 2a including a program; 3, pallets being conveyed by the first peripheral device 2; 4, a second peripheral device comprising a work material supplying conveyor whose end is set close to the industrial robot 1, the conveyor being a gravity conveyor for conveying work materials 5; 5′, work materials 6 stacked on the pallet 3; 6, a memory unit for storing the step of the program which is effected when the industrial robot 1 is stopped unintentionally; 7, detectors provided above the industrial robot 1 and the first and second peripheral devices 2 and 4, each detector comprising an image recognizing device; 8, a control device which comprises an I/O port 8a and a computer 8e including a RAM 8b, a CPU 8c and a ROM 8d; 9, a restarter; 10, a program control unit; and 11, an annunciator. In the industrial robot system thus organized, normally with the work materials 5 and the pallet 3 supplied, the industrial robot 1 operates to stack the work materials 5 on the pallet 3 according to the predetermined program executed by the control device 8. When the industrial robot system is stopped unintentionally, then a countermeasure is taken as shown in Fig. 4, a flow chart. When the industrial robot system is stopped unintentionally for instance because the industrial robot 1 becomes out of order, or the power supply is stopped (Step 101), then in Step 102 the steps of the programs which are effected for the industrial robot and the peripheral devices when the system is stopped unintentionally are stored in the memory unit 6, and in Step 103 the conditions of the robot and peripheral devices provided when the system is stopped unintentionally are detected by the detectors 7. Then, Step 105 is effected after Step 104. When, in Step 105, the steps of the program which have been stored as described above coincide with the results of detection by the detectors, then Step 106 is effected so that the industrial robot system is started again by the restarter 9. If, in Step 105, the steps of the programs stored do not coincide with the results of detection, then in Step 107 the program control unit 10 searches for the steps of the programs which correspond to the results of detection of the conditions obtained when the system is stopped unintentionally (hereinafter referred to as "a program step search operation", when applicable). Then, Step 105 is effected again after Step 108 and Step 109. When, in Step 105, the steps of the programs thus searched for coincide with the results of detection of the conditions, then in Step 106 the system is started again. However, if the coincidence cannot obtained even after the above-described program step search operation is carried out, then the same operation is carried out again. If, although the program step search operation has been carried out three times, the steps of the programs thus searched for do rot coincide with the detected conditions of the robot and the peripheral devices, then it is determined that a trouble occurs with the system; for instance, the work materials 5 have dropped off the robot 1, or the peripheral devices damaged. Hence, Step 110 is effected, so that the annunciator 11 is energized to output an alarm signal or the like, and the restarting of the industrial robot system is not carried out. That is, when stopped unintentionally, the industrial robot system is operated correctly again, or depending on the conditions it is not restarted giving an alarm for the occurrence of a trouble. As was described above, the industrial robot system of the invention comprises: the memory unit for storing the steps of the programs effected when the system is stopped unintentionally, the detectors for detecting the conditions of the robot and the peripheral devices when the system is stopped unintentionally, and the restarter, which is energized when the outputs of the memory and the detectors coincide with each other. Furthermore in the industrial robot system, the program control unit searches for the steps of the programs which correspond to the outputs of the detectors, and when it is impossible to restart the system, the latter is left as it is with the annunciator energized. Thus, when stopped unintentionally, the industrial robot system is operated correctly again, thus contributing to improvement of the productivity; and when it is impossible to restart the system, an alarm is given for the occurrence of the trouble with the system, thus enhancing the safety of the system.

Claims: An industrial robot system, comprising a control means (8) including programs to operate an industrial robot (1) and a peripheral device (2, 4) of said industrial robot (1) according to said programs; a memory means (6) to store the steps of said programs which are effected when said industrial robot (1) and peripheral device (2, 4) are stopped unintentionally; a detector means (7) to detect the condition of said industrial robot (1) and peripheral device (2, 4) when said industrial robot (1) and peripheral device (2, 4) are stopped unintentionally; a restarter means (9) to restart said industrial robot (1) and peripheral device (2, 4); and a program control means (10) to activate said restarter means (9) when the contents of said memory means (6) coincide with the conditions detected by said detector means (7); characterized by said program control means (10) being adapted to search the steps of said programs which correspond to the conditions detected by said detector means (7) when the contents of said memory means (6) do not coincide with the conditions detected by said detector means (7), and to activate said restarter means (9) when a coincidence of the steps of said programs with the conditions detected by said detector means (7) is found, to restart said industrial robot (1) and peripheral device (2, 4) from said steps of the programs. An industrial robot system as claimed in claim 1, further comprising an annunciator means (11) which operates when said program control means (10) cannot find a coincidence of the steps of said programs.

Inventors: FUJITA AKIRA C O MITSUBISHI DE, KATO HISAO C O MITSUBISHI DENK, FUJITA, AKIRA, C/O MITSUBISHI DENKI K.K., KATO, HISAO, C/O MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1990
Main classification: G05B19
IPC codes: G05B19, B25J9, B25J19