| 摘要 |
PURPOSE:To prevent a runaway state of a robot by detecting the disconnection of a feedback line through a latching circuit according to the existence of a pulse train supplied from a rotary encoder, and an output signal from an error counter. CONSTITUTION:When a feedback line 20 goes to a disconnected state, an A phase pulse and a B phase pulse are superposed in a timing and come not to rise within a prescribed time. Therefore, the output of an NAND circuit 32 goes to ''1'', and FFs 38, 40 are not reset. One signal which reaches a D terminal of the FF40 through a Q terminal of the FF38 of a latching circuit by a clock pulse next OR circuit 46 is set to the FF40 and energizes an alarm circuit or a disconnection detecting device, which is not shown in the figure. If the output of this disconnection detecting device is led into a driving controlling circuit of a robot and it is de-energized, a runaway caused by a disconnection of the feedback line of the robot is prevented effectively. |
