Profiling control apparatus and control method thereof

Abstract

An improved profiling control apparatus controls a profiling machine so that the apparatus judges whether an exact profiling operation is performed by the machine at a place where a surface shape of the model to be profiled is suddenly changed, for example at a step, without jumping of a stylus from the model surface, and the profiling machine performs the exact profiling operation without jumping of the stylus. The profiling control apparatus, which detects a displacement of the stylus pressed on the model surface from a tracer head and controls the profiling machine in accordance with the displacement detection signal, includes a displacement compounding unit for compounding three dimensional displacement signal .epsilon.x, .epsilon.y and .epsilon.z to produce a displacement signal .epsilon.(=.sqroot..epsilon.x.sup.2 +.epsilon.y.sup.2 +.epsilon.z.sup.2), a displacement differentiating unit for differentiating the displacement signal to produce a differentiated value d.sup.2 .epsilon./dt.sup.2, a comparison voltage producing unit for producing a comparison voltage Vc corresponding to a maximum acceleration .beta.max of the pressed stylus which can be produced thereon, and a comparison unit for comparing the comparison voltage Vc with the differentiated value d.sup.2 .epsilon./dt.sup.2 to produce a jumping detection signal when d.sup.2 .epsilon./dt.sup.2 =Vc. The profiling control unit is particularly suitable for profiling the model surface of which a shape is suddenly changed.