GB1410051A - Remote angle measurement - Google Patents

Abstract

1410051 Measuring angles electrically M K RUSSELL and A W RUSSELL 4 Jan 1973 [12 Jan 1972] 1537/72 Heading G1N A transducer arrangement for providing signals indicative of angles of pitch and roll, i.e. angles about perpendicular axes for the inclination of the head of drilling tool in a borehole comprises, Figs. 1 and 5, a mass 2 which under gravity causes a rod 3 to bend causing variation in two pairs of differential capacitors formed by the body 2 with four fixed capacitor plates 6, the arrangement providing a signal whose amplitude is dependent on the pitch and whose phase depends on the roll. As shown in Fig.7 signals of A cos wt. and A sin wt. are fed to primary windings 33, 34 of transformers whose secondary windings are centre tapped to earth and connected to opposite plates 6a 6a, 6b 6b respectively. The output signal derived from the body 2 is given by A sin # sin (wt-#) where # is pitch angle and # is roll angle. This output is fed to phase locked loop circuit 38 which provides a squarewave constant amplitude signal with the same zero-crossing points as the input. This signal is used as a demodulating signal in 3 circuits. In circuit 40 it demodulates A sin # sin (wt-#) and yields after integration K sin #. In circuit 39 it interrupts the signal A cos wt. and after integration yields K sin #, whilst similarly in circuit 41 K cos # is obtained. A resolver gives # from K sin # and K cos #. Details of the transducer are provided Fig.6 (not shown), which disclose an arrangement wherein the mass 2 is oil immersed and a closed bellows is provided in the oil chamber to allow for thermal expansion.