| 摘要 |
<p>A method of accurately detecting the abnormality of a load, such as the fusion at a free end of a spot gun. In this load abnormality detecting method, while a flag F2 which is set to ''1'' when an instruction for moving a movable mechanical part is outputted, and which is reset to ''0'' after a predetermined very short period of time has then elapsed, is in ''0'' because the movable part is stopped, estimated disturbance torque T0 is first determined successively by a disturbance estimating observer, updated and stored (S4, S11). When an instruction for moving the movable mechanical part is outputted and the flag F2 is set to ''1'', an estimated disturbance torque T1 is determined (S5). When an absolute value [T1-T0] of the difference between this torque T1 and estimated disturbance torque T1 determined immediately before the starting of the movable mechanical part exceeds a reference level Ts (S6), an alarm representing the occurence of a load abnormality is given (S7), and a flag F1 is set to ''1'' to stop the operation (S3, S8). The estimated disturbance torque T0 during the stoppage of the movable mechanical part represents a value such as the gravity which this part receives during this time. Consequently, the value, [T1-T0] represents the disturbance torque, from which the influence of gravity is eliminated, during the movement of the mechanical part. By comparing this value with the reference value Ts, a force exerted on the movable part, other than the gravity and a frictional force, can be detected more accurately. Therefore, abnormality, such as the occurrence of fusion can be determined accurately.</p> |
