Appeal No. 1999-1578
Application 08/764,508
The invention relates to a method of detecting an abnormal load acting on a servomotor which
drives a cutter of a machine tool or a robot arm and controlling the servomotor when such abnormal
load is detected.
Independent claim 1 is reproduced as follows:
1. A method of detecting an abnormal load on a servomotor driving a machine and controlling
the servomotor in such an abnormal condition, comprising the steps of:
(a) rotating a servomotor in a first direction to drive a machine tool;
(b) detecting an abnormal load acting on the servomotor during a driver
operation and due to a large torque developed by the rotation of said servomotor in said first direction
when an obstacle collides with said machine tool causing an elastic deformation on said machine tool;
(c) executing a position loop processing using an error register for storing a positional deviation
value;
(d) setting a predetermined positional deviation having a direction opposite to said first direction
in said error register when said abnormal load is detected; and
(e) rotating the servomotor in the direction opposite to the first direction by a predetermined
rotational amount corresponding to said predetermined positional deviation and then stopping the
servomotor, to release said elastic deformation of said machine tool.
Examiner relies on the following references:
Eto et al. (Eto) 4,580,085 Apr. 1, 1986
Arita et al. (Arita) 5,304,906 Apr. 19, 1994
(filed Aug. 23, 1991)
Claims 1, 2 and 4 stand rejected under 35 U.S.C. § 103 as being unpatentable over Arita and
Eto.
2
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