Control of torsional deformation of elongate members

Apparatus for controlling the resistance of an elongate member to torsional deformation between its ends comprising a torque transmitting member mounted coaxially with the longitudinal axis of the elongate member and fixed at one of its ends to the member, the other end of the torque transmittng member being capable of rotation about its axis relative to the elongate member, measuring means operable to measure torsional deformation of the elongate member to produce a control signal indicative of the sense and magnitude of the deformation, actuating means responsive to the control signal to apply a torque to the other end of the torque transmitting member about the axis thereof in such a sense as to cause the said one end of the elongate member to be rotated relative to the other end thereof to oppose the torsional deformation, wherein the measuring means comprises transducer means having a first part fixed to the elongate member at said one end of the torque transmitting member and a second part fixed to the elongate member at said other end of the torque transmitting member, the transducer means being responsive to rotation between the first and second parts thereof to produce a transducer signal indicative of the degree of rotation and a signal processing arrangement responsive to the magnitude of the rotation measured to produce the control signal for the actuation means, and wherein the first and second parts of the transducer means comprise a source of light and a receiver thereof located at opposite ends of the elongate member, the receiver being responsive to a beam of light received from the source and displaced from the longitudinal axis of the elongate member to provide the transducer signal.

Apparatus for controlling the resistance of an elongate member to torsional deformation between its ends comprising a torque transmitting member mounted coaxially with the longitudinal axis of the elongate member and fixed at one of its ends to the member, the other end of the torque transmitting member being capable of rotation about its axis relative to the elongate member, measuring means operable to measure torsional deformation of the elongate member to produce a control signal indicative of the sense and magnitude of the deformation, actuating means responsive to the control signal to apply a torque to the other end of the torque transmitting member about the axis thereof in such a sense as to cause the said one end of the elongate member to be rotated relative to the other end thereof to oppose the torsional deformation, wherein the measuring means comprises transducer means having a first part fixed to the elongate member at said one end of the torque transmitting member and a second part fixed to the elongate member at said other end of the torque transmitting member, the transducer means being responsive to rotation between the first and second parts to produce a transducer signal indicative of the degree of rotation, and a signal processing arrangement responsive to the magnitude of the rotation measured to produce the control signal for the actuation means, and wherein the first part of the measuring means comprises a source of light and a receiver thereof each located at the same end of the elongate member, the source being arranged to transmit a beam of light along the elongate member to the second part comprising a reflector at the other end of the member arranged to reflect the beam to be incident on the receiver to provide the transducer signal.