CYLINDER POSITION MEASUREMENT DEVICE, AND CYLINDER POSITION MEASUREMENT METHOD

摘要

PROBLEM TO BE SOLVED: To accurately measure a stroke amount of a cylinder even when a high pressure of oil in the cylinder is applied.SOLUTION: An arithmetic processing section 400 identifies a maximum pressure Pmax while a direct-acting member moves for a certain section and determines a pressure correction amount &Dgr;Sp at a peak position of a waveform detected by a magnetic force sensor 302 on the basis of a pressure correction table 413, determines a travel speed V of the direct-acting member on the basis of the variation in stroke amount Sd and determines a speed correction amount &Dgr;Sv at the peak position of the waveform detected by the magnetic force sensor 302 on the basis of a speed correction table 423, adds the pressure correction amount &Dgr;Sp and speed correction amount &Dgr;Sv to the stroke amount Sd indicating the peak position of the waveform detected by the magnetic force sensor 302 to determine a corrected correction stroke amount Sc, and resets the origin position of the stroke amount on the basis of the correction stroke amount Sc.