Patent ID: 6366532
Filing Date: 2002-04-02
Classification: B66B,G01B,G01S

Abstract:
An apparatus for detecting the position of an object moveable along a predetermined travel path, comprising:an acoustic signal waveguide extending along the travel path and having a predetermined, uniform speed of propagation of sound; a signal input coupler located on the moveable object, to couple a clocked acoustic signal into the acoustic signal waveguide, signal output couplers at both ends of the acoustic signal waveguide and each being connected to an evaluation unit for determining the propagation-time difference of the sound signal from a position at which it is coupled in to the signal output couplers and for generating a signal representative of the instantaneous position of the moveable object on the travel path, wherein a calibration signal input coupler connected to a calibration acoustic signal generator for a calibration acoustic signal is provided on one of the signal output couplers, the evaluation unit calculating a correction variable for subsequent determinations of position from the calibration path passed through by the calibration acoustic signal to the other signal output coupler and the propagation time of the calibration acoustic signal over the calibration path.