SE7907208L - LEGESBESTEMNINGSUTRUSTNING - Google Patents

Abstract

The invention concerns a position determining arrangement designed for noncontact indication of position along an axis of an object 1 which is moving along the axis. The position of the object has to be given with very small time interval, for example, on the order of 1-5 ms or less between each measurement event. In order to achieve these tightly spaced measurements, there is a position indication arrangement 3 which gives an accurate current position of the object with more widely spaced time interval than the desired close time intervals. This position indication arrangement 3 is preferably an electronic distance measuring, EDM instrument, which measures the distance between a fixed point 4 and a point on the moving object. Instead of or as a supplement to the EDM instrument, however, the position indication arrangement can also contain position indicators 13-15 of electrooptical type, for example, where a light beam is interrupted by the moving object. Several position indicators of this kind can be placed along and athwart the axis and give an indication each time the object has reached a predetermined position. Since the position indication arrangement is not able to provide measurements with the desired narrow time interval, a data transmitter 5 is situated on the object. This data transmitter comprises either a speed indicator with an electronic unit which integrates the reading of the speed indicator with regard to time or an accelerometer with an electronic unit 6 which double-integrates the reading of the accelerometer with regard to time. During the desired narrow time interval, the electronic unit in the data transmitter calculates the current position of the object by correcting the instantaneous value of the measurement signal from the data transmitter with the position obtained at one or more of the immediately preceding position determinations. Whenever an output signal is obtained from the position indication arrangement, the position given by means of the data transmitter is corrected to the same position as indicated by the position indication arrangement. <IMAGE>