British Aerospace Public Limited Company

Malcolm P Varnham

Diana M Hodgins

Timothy S Norris

James McInnes

Huw D Thomas

Charles Day

Hugh D Thomas

A vibrating cylindrical rate sensor (10) is mechanically balanced and mode aligned with respect to the vibrating portion of the sensor (10) by removing material from a vibrating portion of the vibrating cylinder (34) after the drive and pick-off transducers (30, 32, 30a, 18, 20) are fixed to the vibrating portion of the vibrating cylinder (34) of the cylindrical rate sensor (10).

Method of minimizing bias and achieving mode alignment by trimming a

A method of and apparatus for scale factor compensation for piezo-electric rate sensors maintains the magnitude of vibration at a primary pick-off point substantially constant to enable one of the variables of a vibrating structure--the piezo-electric charge coefficient .beta. to be determined, and thereby enables variation of the scale factor of the sensor from a calibrated value to be determined. This enables correction of the sensor output by a computational scale factor control unit to ensure that the output therefrom allows for a more accurate sensor. Thus, sensors are provided for applications requiring a higher degree of accuracy than they were previously able to provide for.

Scale factor compensation for piezo-electric rate sensors

Method of balancing a vibrating rate sensor by removing a portion of the

A single axis rate sensor comprising a cylinder positioned about an axis and having primary and secondary drive and pick-off transducers and primary and secondary control loops. The primary control loop is provided for maintaining resonance of the cylinder by generating a ninety-degree phase shift between the primary drive transducer and the primary pick-off transducer. The secondary control loop is provided for receiving a signal from the secondary pick-off transducer indicative of rotation of the cylinder and for nulling the secondary drive transducer to zero. The primary control loop includes a phase-locked loop having a phase detector configured to operate at quadrature. By operating the demodulator in quadrature the demodulator and loop filter combination are a linear device which will not mix the microphonic baseband signal with the carrier. There will therefore be a reduction and possibly an elimination of the modulation of the voltage controlled oscillator by microphonic noise.

Single axis rate sensor noise reduction

A vibrating planar ring or hoop-like structure is disclosed. The structure is suspended in space by a suitable support mount for detecting turning rate, linear acceleration and angular acceleration. Turning rate is sensed by detecting vibrations coupled by Coriolis forces, whereas linear acceleration and angular acceleration are sensed by lateral, vertical and rocking movement of the entire ring or hoop-like structure within its mount.

Vibrating planar gyro

This invention relates to a single axis solid state attitude sensor in which, the spatial orientation of a resonant rode on a resonant body is maintained in alignment with the inertial angle K8 of the resonant body.

Single axis attitude sensor

A fibre optic gyroscope which reduces the sensitivity of the gyroscope to offsets in the demodulator, the reduction in sensitivity being achieved by modulating the radiation passing through the gyroscope by a first waveform which is derived from second and third periodic waveforms, the third waveform having a frequency substantially less than that of the second waveform in use and the second waveform having a frequency of about 1/2T where T is the time taken for the radiation to travel through the gyroscope, and detecting said radiation which is subsequently demodulated with respect to both second and third waveforms in order to minimize any offset introduced by the demodulation with respect to the second waveform.

Reduction of demodulator offset errors in fibre-optic gyroscopes

This invention relates to a method and apparatus, i.e. a 'wavelength meter', for determininhg the wavelength of optical radiation, e.g., visible radiation. Radiation is subjected to two or more wavelength dependent phase modulations having a net effect which is wavelength dependent and is zero at a predetermined wavelength. The net modulation is then determined so as to obtain the difference between the predetermined wavelength and the actual wavelength of the radiation.

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Plymouth, United Kingdom

Malcolm P Varnham