| 摘要 |
PURPOSE:To eliminate the use of a limit switch involving a fluctuating tendency, by providing computation of the real stopped position of the moving portion from the position stopped, speed, and moving direction of the moving portion when the power failed and the time constant relative to the intrinsic inertia of the moving portion. CONSTITUTION:When the power recovers, a computing unit 23 reads out the position data P0 and the speed data V0 of a slide table 1 at the time of the power failure from a travel detecting circuit 21 and a speed register 22. The computing unit 23 also computes the position stopped of the slide table 1 when the power failed based on time constant data dependent on the time lag of the braking action at the time of the power failure and the damping time constant due to inertia of a direct current motor 4, etc. Then a motor 4 is slowly rotated by a command from a travel setting unit 10 through a controlling mechanism 17, and pulses from a pulse generator 9 are counted until the signal for one full turn of the motor is received. The present position is computed also with the result of the counting, and the data in a position register 13 is rewritten. Thus, the limit switch at the original point can be eliminated and it becomes unnecessary to return the moving position to the original point. |
