I²。+J²。=R²加工点M相对圆弧有三种情况
- @1 u* k" T; F5 _% x9 O& m- [' g在圆弧外:Ii²+Ji²-R²>0
S7 C$ ~% ~+ Z* O$ U在圆弧上:Ii²+Ji²-R²=0 图5.3
, Z$ O8 F7 s6 N4 B8 ^3 U! |在圆弧内:Ii²+Ji²-R²<0
5 l0 }! {6 R g" ^, V程序框图 (数控指令G00/G01 X— Y—) $ [1 g, H; h( Z b1 [
取Fi=Ii²+Ji²-R² (偏差判别函数)# m+ M, j# W/ T t/ ~. _2 R
规定I象限时内:+Y方向走一步$ f( N9 d: s, r! W' k% q
外、上:-X方向 走一步, S5 r: ]8 u6 t5 J9 Y1 P6 c
-X走一步后:Ii+1=Ii-1 ,Ji+1=Ji
$ z$ k, u+ Y$ |Fi+1=Ii+1²+Ji+1²-R²=Fi-2Ii+1 6 v" f' P/ s6 t
+Y走一步后:Ii+1=Ii ,Ji+1=Ji+1 P+ @- i# D% r# l- Z; m/ c! J
Fi+1=Fi+2Ji+1 ) r; O; g% j6 t' W
我们可推导第一象限的顺圆。) v1 j2 c! O; r6 x: v x3 L
+X走一步后:Ii+1=Ii+1 ,Ji+1=Ji " B: p4 c2 s* N7 F2 N+ R
Fi+1=Fi+2Ii+1 (5-7)
0 T' B( Y( o3 |6 V& y/ \7 c9 T-Y走一步后:Ii+1=Ii ,Ji+1=Ji-1
% a6 `) W1 e) r/ _4 ]Fi+1=Fi-2Ji+1 (5-85 x: Z' H# o* h4 u* ]* p
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