By using the method of documentary investigation,experimental testing and geometric proof,the author finds that if put datum point of checking speed skate is on the edge of skate,it makes measurement basis change,the result of radian measured can not reflect real curve shape.

Improve on traditional interpolated algorithm in CNC system—arc cutting method;

This paper analyzed how to use reflective high frequency non contact eddy sensor for detecting the tension and back arc of band saw,in the circuitry principle,and presented its benefit for mending band saw after the detector is used.