On-The-Fly CNC interpolation using frequency-domain FFT-based filtering

Abstract

Finite Impulse Response filtering is increasingly becoming the interpolation method of choice in modern computer numerically controlled (CNC) machining centres. Recently, On-The-Fly (OTF) interpolation was introduced using direct convolution to adaptively change the FIR flter time constant throughout the toolpath. In this paper, it is shown that computational advantages can be gained by using frequency domain methods instead. This paper introduces a novel on-the-fly CNC interpolation method using Fast Fourier Transforms (FFTs). The presented OTF FFT method demonstrates up to 10 times increase in computational speed than the direct convolution OTF method. The effectiveness of the proposed method is validated in simulation based case studies.