I²。+J²。=R²加工點M相對圓弧有三種情況
8 E$ Z7 c2 Q; y6 {+ `% r! P在圓弧外:Ii²+Ji²-R²>0
1 B' @8 ^5 w, y1 f4 p6 H' K在圓弧上:Ii²+Ji²-R²=0 圖5.3
& _. A; c; b6 L s3 |5 Z" E2 i在圓弧內:Ii²+Ji²-R²<0& W U; o. B, m
程序框圖 (數控指令G00/G01 X— Y—) - s+ i; M/ Z3 C# f
取Fi=Ii²+Ji²-R² (偏差判別函數)# Z: r. q" V T! h0 ^0 f( [
規定I象限時內:+Y方向走一步( I& \4 H/ _: ~2 [
外、上:-X方向 走一步
+ K% _8 H# \) t1 X-X走一步后:Ii+1=Ii-1 ,Ji+1=Ji
2 U$ l+ `6 o5 t( K( v. VFi+1=Ii+1²+Ji+1²-R²=Fi-2Ii+1
5 {1 d' d9 ?1 e! k$ C: ?+Y走一步后:Ii+1=Ii ,Ji+1=Ji+1: A$ t5 W7 `, l8 S" {
Fi+1=Fi+2Ji+1
6 y, f# {! v; T1 [" B. ]$ ~# m我們可推導第一象限的順圓。# w9 P G6 t2 [* @
+X走一步后:Ii+1=Ii+1 ,Ji+1=Ji
% }# a7 A6 k2 G2 S" s GFi+1=Fi+2Ii+1 (5-7)
3 o* u7 B3 ^+ m- k2 A2 j6 v-Y走一步后:Ii+1=Ii ,Ji+1=Ji-1
5 V: i/ Q: j* k, C+ RFi+1=Fi-2Ji+1 (5-8
( t* ]" r5 x% Y1 @5 K* i |