# Improve the measure of DDA interpolation quality

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- source:WEINBERG CNC Machining

5 (call half to load) two kinds. "Half to load " it is to be before DDA iteration, the initial value of remainder register JRx and JRy is not buy 0, however buy 1000... 000 (namely 0.

5) , that is to say, the highest and significant position remainder register JRx and JRy " 1 " , the others everybody all buy " 0 " , such, as long as again overlay 0.

5, remainder register can produce the first to spill over pulse, make integrator spills over ahead of schedule. This is in the function that be accumulated is lesser, when cannot producing the situation that spill over tardy, have very great real sense, because it was improved,spill over the time of pulse distributings, reduced interpolation error. "Half to load " can make the error of linear interpolation reduces less than of half pulse equivalent, the example of a clearly is: If the start of linear OA is coordinate origin, terminal coordinate is A (15, 1) , not " half to load " when, x integrator did not spill over except first time iteration outside, 15 times iteration all has the rest spill over; And Y integrator just has when the 16th iteration only spill over pulse (see a picture 2, 17 (A) . If undertook " half to load " , criterion X integrator did not spill over except the 9th iteration outside, the others all has 15 times spill over; And of Y integrator spill over to have to the 8th iteration ahead of schedule spill over, this was improved spill over the time of pulse distributings, raised interpolation precision (see a picture 2, 17 (A) . Graph 2-17 " half to load " the contrail after " half to load " make the precision of circular arc interpolation gets clear improvement. Be like pair of graphs 2, 17 (B) example undertakes " half to load " , its interpolation contrail is like the broken line place in the graph to show, interpolation process sees a table 2, 7. After be being compared carefully, can discover, "Half to load " make of X integrator spill over pulse shifted to an earlier date, raised interpolation precision thereby. Alleged " full to load " , it is what to become the initial value place of remainder register JRx and JRy this register is in before DDA iteration most high capacity is worth (should be N when, namely buy enters 2n-1) , the generation of coordinate integrator in advance that this meeting makes numerical value of the case that be accumulated very little spills over, interpolation precision gets clear improvement. Graph 2-18 " full to load " the actual contrail after pursues 2, 18 it is to use " full to load " the interpolation contrail that the method gets, because be accumulated,function register and remainder register all are 3, buy is into the largest number 7 (111) . CNC Milling