Abstract: A diagnostic method in which data obtained from a real-time sensor are stored during the operation of a robot for later diagnosis of the operation state of the sensor. This method includes the steps of scanning an object by using a laser sensor, thereby obtaining sectional data; detecting a weld line position on the basis of the sectional data; storing in a memory the weld line position along with robot positions corresponding to the time of detection; and storing in the memory the sectional data when a predetermined robot position is reached with a conditional value set to "1", when the weld line position has first failed to be detected with the conditional value set to "2", or when the variation of the weld line position is larger than a predetermined value. The operation state of the sensor is traced on the basis of the weld line position and the sectional data stored in the memory, and various parameters for detection are set so that an optimum state for detection can be established.

Abstract: The present invention relates to a position detecting method and its apparatus that is capable of improving detecting accuracy in a laser sensor using a Charged Coupled Device (CCD) as a light receiving element. A sum of products of an output C.sub.i of each cell in a light receiving element and a cell position X.sub.i is obtained, and the cell outputs C.sub.i are added. When the cell output C.sub.i exceeds a predetermined threshold value, a counter is reset. When the cell output C.sub.i decreases down below the threshold value, the sample hold signal SH is counted. When the counted value of the counter becomes a predetermined value, a division circuit divides the above-obtained sum of products by the above addition value to obtain a center of gravity of the sum of products as a light receiving position. Then, thus obtained value is stored in a latch buffer.

Abstract: The purpose of the invention is to properly determine the replacement time of a guard window of an arc sensor using an original function of the arc sensor.The apparatus for monitoring a guard window of an arc sensor according to the present invention is provided with an arc sensor guard window (28) mounted on an arc sensor unit (20) and a standard reflecting plate (30) located at a position a determined distance from the front surface of the guard window (28). And the apparatus detects the reflected light (27) from the standard reflecting plate (30) when a laser beam (26) scans the standard reflecting plate (30), before the guard window (28) is used for an arc welding operation. The apparatus memorizes the quantity of detected light reception as the first quantity. The apparatus then detects the reflected light (27) from the standard reflecting plate (30) in the same way as before, after the guard window (28) is used for an arc welding operation.

Abstract: An operation control system for a scanning galvanometer associated with an arc sensor (20) of a welding robot for sensing a weld line, and having a swing mirror (23) integral therewith for a laser beam scanning. A memory (43) stores waveform data of a galvanometer drive command current obtained by synthesizing a constant-speed command current and an acceleration/deceleration command current, and an address circuit (42) causes the waveform data to be output from the memory (43) at predetermined intervals. A D/A converter (44) converts the output of the memory (43) to an analog value, and a scanner drive circuit (45) drives the galvanometer (22), which swings the swing mirror (23) to detect the weld line.

Abstract: An optical distance sensor superior in measuring accuracy and simple in construction is mounted to, e.g., a welding torch of an arc welding robot. A laser beam from a laser oscillator (1) is moved on a workpiece (100) in a direction perpendicular to a weld line, with angular movement of a mirror (2). Primary reflected light, secondary reflected light and spatter light, except for arc light intercepted by a filter (5), are incident via a lens (4) on light receiving cells of a light receiving section (3) composed of a one-dimensional charge-coupled device. At scanning of the light receiving section, outputs of the light receiving cells depending on incident light quantities are successively sent, and data specifying those light receiving cells which generate predetermined level outputs are written in one of memory buffers (12, 13).

Abstract: An arc sensor (10) to be attached to an arc welding torch for detecting a welding spot is provided with an optical detecting system having an optical position detector (14), an objective lens (18), and a transparent objective window (20) arranged in front of the objective lens, and a plurality of arc light screening plates (22 and 24) made of an opaque material, and having a light transmitting apertures (22a and 24a), the plurality of arc light screening plates (22 and 24) being arranged in front of the transparent objective window (20) and spaced from one another for screening an arc light but permitting the detecting light beam to pass therethrough.

Abstract: An industrial robot having a dust-proof structure is equipped with at least one dust cover having an opening at one end thereof and a linearly movable unit extending through the opening of the dust cover and movable back and forth in the longitudinal direction thereof. Suction is exerted by a suction unit inside the dust cover so that air is flows from outside the dust cover into the same through the opening. A ring member is disposed at the opening of the dust cover in such a manner as to encompass the outer periphery of the linearly moving unit through a gap. At least one annular groove for reserving air is disposed on the inner peripheral surface of the ring member so as to encompass the outer periphery of the linearly moving unit.