Interpolation apparatus for digital electronic position measuring instrument
AssigneeDr. Johannes Heidenhain GmbH
InventorErnst Schwefel
Life of this patent
Estimating the term…
Abstract
An interpolation process is described for use with an incremental position measuring device which produces a periodic analog output signal. The output signal is digitized and then applied as an input to a digital computer programmed to calculate the interpolation value of the signal. In the preferred embodiment the computer is also programmed to apply a number of corrections to the digitized signal prior to interpolation.
Claims8
An interpolation apparatus for evaluating at least one periodic analog signal generated by an electronic position measuring device having a measuring scale and a scanning unit, moveable relative to the scale, said analog signal having an amplitude which varies in a periodic manner as a function of the position of the scanning unit with respect to the scale, said apparatus comprising:
- digitizing means, responsive to the analog signal, for digitizing the analog signal to generate a first digital signal which corresponds in a predetermined manner with the amplitude of the analog signal;
- a digital computer responsive to the first digital signal;
- interpolating means, included in the computer, for generating an interpolation signal in response to the digital signal, said interpolation signal being representative of the position of the scanning unit with respect to the scale and having a higher resolution than the spatial period of the periodic analog signal;
- and
- evaluating means, also responsive to the analog signal, for generating a second digital signal representative of the position of the scanning unit with respect to the scale, said second digital signal having a spatial resolution lower than that of the interpolation signal.
An interpolation apparatus for evaluating first and second periodic analog signals generated by an electronic position measuring device having a measuring scale and a scanning unit, moveable with respect to the scale, said first and second periodic analog signals having a substantially fixed phase relationship, each of said periodic analog signals having an amplitude which varies in a periodic manner as a function of the position of the scanning unit with respect to the scale, said apparatus comprising:
- digitizing means, responsive to said first and second analog signals, for digitizing said first and second analog signals to generate first and second digital signals which correspond in a predetermined manner with the amplitudes of the first and second analog signals, respectively;
- computer means, responsive to the first and second digital signals, for generating an interpolation signal from the first and second digital signals such that the interpolation signal is representative of the position of the scanning unit with respect to the scale, said interpolation signal having a spatial resolution higher than the spatial period of the first and second periodic analog signals;
- and
- evaluating means, also responsive to the first and second analog signals, for generating a third digital signal representative of the position of the scanning unit with respect to the scale, said third digital signal having a spatial resolution lower than that of the interpolation signal.
An interpolation apparatus for evaluating first and second periodic analog signals generated by an electronic position measuring device having a measuring scale and a scanning unit, moveable with respect to the scale, said first and second periodic analog signals having a substantially fixed phase relationship, each of said periodic analog signals having an amplitude which varies in a periodic manner as a function of the position of the scanning unit with respect to the scale, said apparatus comprising:
- counter means, responsive to the first and second analog signals, for maintaining a running count representative of the cumulative number of cycles of the first and second analog signals;
- digitizing means, responsive to said first and second analog signals, for digitizing said first and second analog signals to generate first and second digital signals which correspond in a predetermined manner with the amplitudes of the first and second analog signals, respectively;
- a digital computer, responsive to the count and the first and second digital signals;
- means, included in the computer, for generating an interpolation signal value from the first and second digital signals such that the interpolation signal is representative of the position of the scanning unit with respect to the scale, said interpolation signal having a spatial resolution higher than the spatial period of the first and second analog signals;
- means, included in the computer, for combining the interpolation signal with the count to generate a composite signal;
- and
- display means, responsive to the composite signal, for displaying the composite signal.
Dependencies are inferred from the claim text.