The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 14, 1989
Filed:
Oct. 29, 1987
Kabushiki Kaisha SG, Tokyo, JP;
Abstract
A coil assembly including primary coils disposed at predetermined locations axially spaced from one another and secondary coils provided in association with these primary coils is fixed at one end of a fluid powered cyliner. A piston rod is slidably disposed through a space in the primary and secondary coils. Rings made of magnetic substance are provided on the piston rod with a predetermined axial interval therebetween. Each of the primary coils is excited with one of reference AC signals which are out of phase with one another and an output signal which is electrically phase-shifted in accordance with the position of the piston rod is obtained as a sum of output signals from the secondary coils. Piston rod position data is obtained by measuring the amount of the phase-shifting and is utilized for positioning control of the cylinder. The velocity and acceleration of the movement of the piston rod are detected on the basis of the detected position data and the amount of overrun is estimated in accordance with the detected velocity and acceleration to effect the most accurate positioning control. Each time the positioning is completed, the amount of overrun is corrected to improve the accuracy of a next positioning control.