GB1414972A - Method of conversion of shaft rotation angle into an electric signal - Google Patents

Abstract

1414972 Measuring shaft rotation angles CHELYABINSKY POLITEKHNICHESKY INSTITUT IMENI LENINSKOGO KOMSOMOLA 1 Nov 1972 50413/72 Heading G1N The range over which a shaft rotation angle transducer operates linearly is extended by resetting the transducer each time it reaches the end of its linear range. When the transducer output reaches a predetermined value which corresponds to the end of the linear range it is reset (by adjusting its connections, for a sine-cosine transducer) to the other end of the range; this produces a change in the output level which is countered by generating a separate signal equal and opposite to this change. The final output representing the shaft rotation angle is thus the sum of the transducer output and the separately generated signal. In Fig. 3 the transducer is a rotary transformer 33, which has a linear output for angles in the range Œ#/3. Its windings are initially connected by a commutating switch 36 as shown by the dashed lines in the switch. The transformer is fed by power supply 35, and its output is taken from switch terminal 50. Suppose that the shaft is rotated from 0 to +#/3; when the latter value is reached the output at contact 50 becomes equal to a preset level, and this is detected by threshold device 58. This actuates logic device 59 to change the commutating switch 36 so that the transformer is reconnected and set to the -#/3 end of its range. This causes the output at 50 to change, which is countered by an equal and opposite signal generated at 39, also under control of the logic device 59. The output from 50, and the signal from 39, are summed at 38 to give a final output at 40. Rotation may now continue until +#/3 is again reached, in which case the procedure repeats. The device 39 is a transformer 62 having several secondary winding taps each giving an output equal to the change of output at 50 when resetting occurs; switch 61 selects the taps. The transformer 62 is fed by power supply 35, so that variations in the supply levels affect the transducer 33 and transformer 62 equally and are cancelled. In place of the electrical connection between the rotary transformer output 50 and threshold device 58, the latter may be actuated by any other transducer which supplies a signal when the shaft has rotated through a given angle. The various inter-connections set by commutator 36 as the shaft rotates are given in Tables 1 and 2 (not shown).