GB1152709A - Improvements in and relating to Ascertaining the Actual Orientation of a Tunnel Boring Machine in a Three-Dimensional Co-Ordinate System - Google Patents

Abstract

1,152,709. Photo-electric position finding. CONTRAVES A.G. 9 June, 1966 [15 June, 1965], No. 25713/66. Heading H4D. In an arrangement for ascertaining the orientation of a tunnel boring machine a light or infra-red beam (e.g. from a laser) is projected along a longitudinal axis in the direction of the tunnel to be bored, two sensing systems are mounted on the machine, each including a sensor adjustable by servomotor drives in two directions transverse to the longitudinal axis to centre the sensor on the beam, and the positions of the centres of the sensors relative to origins of co-ordinates fixed to the machine are continuously indicated. A sensing system may comprise a disc 31 having a permeable section 310 and being rotated about an axis a 2 ; the disc co-operates with a photocell 38 producing a modulation dependent on the relative positions of axis a 2 and the beam axis A. Reference signals r x , r y are derived from photo-cells 36x, 36y and ensuing error voltages U # , U # are fed from a detector D to control two servomotor drives associated with the sensor so as to align axis a 2 with axis A. Programmed control of desired machine coordinates may be introduced. The detector D incorporates transistor pairs fed with the respective reference signals, Fig. 6 (not shown).