Numerical control apparatus and the friction compensation method

摘要

PROBLEM TO BE SOLVED: To provide a numerical control device and a friction compensation method for estimating friction force or friction torque with high accuracy from a low speed area to a high speed area to correct a quadrant projection even in a feed drive mechanism of a double nut preload system.;SOLUTION: A feed drive mechanism of a double nut preload system generates a first quadrant projection after inversion of the motion direction of a table. A second quadrant projection is generated when the feed drive mechanism of the double nut preload system moves by a predetermined amount after the inversion of the motion direction. The first quadrant projection results from friction torque f₁ and f₂. A first friction characteristic estimation part 26 compensates the friction torque f₁ which suddenly changes after the inversion by an approximate equation 1. A second friction characteristic estimation part 27 compensates the friction torque f₂ which slowly changes after the inversion by an approximate equation 2. The second quadrant projection results from friction torque f₃. A third friction characteristic estimation part 28 compensates the friction torque f₃ which changes after moving by a predetermined amount after the inversion by an approximate equation 3. Therefore, a numerical control device can compensate a rise in friction force to be generated at two stages with high accuracy.;COPYRIGHT: (C)2013,JPO&INPIT