上海维宏电子科技股份有限公司
Weihong Electronic Technology Co., Ltd.
Specialized, Concentrated, Focused - 65 -
5.1.2 Principle of Returning to Machine Origin (with Encoder
Feedback)
With encoder feedback function, the system will execute coarse positioning and fine positioning only
once in returning to machine origin. The retracting distance after fine positioning is the actual retracting
distance adjusted in terms of actual situation. And the concrete process is as below:
D
4
3
2
1
Coarse Positioning Signal Belt
5
B A
Retracting
distance
C
E F
Actual
retracting
distance
6
Legend
1
Initial stage of coarse positioning
2
Over-travel stage after receiving REF. point signal
3
Retracting stage after overtravel in coarse positioning
4
Initial stage of fine positioning
5
Over-travel stage after receiving encoder zero signal
6
Actual retracting stage
Fine Positioning Signal Belt
Fig. 5-5 The process of returning to machine origin
1) In coarse positioning stage, the machine tool should stop immediately at place ―A‖ when receiving
REF. point signal, but it may stop at place ―C‖ due to over-travel caused by inertia and time-lag.
2) The machine executes retracting stage of coarse positioning.
3) In fine positioning stage, the machine tool moves reversely and should stop at place ―D‖ immediately
when receiving encoder zero signal; at the mean time, the feedback data of encoder will be latched,
but the machine will generate over-travel and stop at place E due to inertia and time-lag. And the
displacement between encoder zero signal and stop position (i.e. DE) is the across distance of
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