Minimisation of computation for digital controllers

A novel Structure is described and analysed which has a number of advantages for the practical implementation of recursive digital filters in control applications. It is based upon the use of an established alternative to the usual z^-1 delay operator, but this has been developed into a standard form called a δ filter which is both robust and versatile. The advantages are shown to be in the simplicity of implementation, including the determination of word-lengths for the coefficients and variables. First- and second-order filter structures are given in detail, and simulations presented to demonstrate the operation of a few typical filters. Significant reductions in computation requirements are possible using the δ filter.