Unscented kalman filtering of line spectral frequencies.

A belt grinding machine for forming cutting edges of complex geometry on surgical instruments includes a fixture for holding an instrument with a site thereon in a position for grinding a surface at the site on the instrument, a grinding assembly having a grinding belt with a planar span for grinding the surface at the site on the instrument, an oscillation producing mechanism for oscillating the instrument relative to the grinding belt so as to reciprocally translate the site on the instrument parallel and relative to the planar span of the grinding belt concurrently with grinding the surface at the site on the instrument, a translation producing mechanism for selectively translating the grinding assembly and thus the planar span of the grinding belt toward and away from the site on the instrument to permit receiving and setting up of the instrument in the instrument holding fixture and to place the instrument in a position for the planar span of the grinding belt to grind the surface at the site on the instrument, a grinding angle setting mechanism for selectively changing the angular relationship of the planar span of the grinding belt relative to the site on the instrument to grind another surface thereon, and a grinding site setting mechanism for rotating the instrument relative to the planar span of the grinding belt for selectively changing the location of the site on the instrument.