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Title: Investigation of the behaviour of a dynamically tuned gyroscope with a view of controller design
Author: Maitland, J. K.
Awarding Body: Hatfield Polytechnic
Current Institution: University of Hertfordshire
Date of Award: 1986
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The strapdown dynamically tuned gyroscope (DTG) is a candidate for use as the angular motion sensor in s'trapdown inertial navigation systems and autopilots. However, the dynamic performance of the strapdown DTG is one of the limiting factors restricting usage of the instrument in these systems. This research project considers control strategies to enhance the strapdown DTG performance. The DTG equations of motion are derived, with damping terms, and angular speed components introduced about the spin axis. The DTG equations of motion are solved numerically using a 4th order Runge-Kutta method, and taking advantage of rotating reference frames to eliminate time varying elements in the system matrix. This approach reduces the number of computations per time step and improves numerical stability. The tuning conditions for a multigimbal DTG are derived. A modal analysis is carried out on the DTG system matrix for different tuning conditions. This work provides the basis for the reduction of the DTG equations of motion to a free rotor gyroscope form. A parameter estimation procedure is designed which reflects the sensitivity of the DTG dynamic characteristics to certain parameters. A comprehensive experimental programme is carried out to validate the DTG mathematical model and estimate the numerical value of critical DTG parameters. A control strategy which processes the torquer and demodulator signals of the strapdown DTG is formulated. This strategy, used on the strapdown DTG, improves the diagonal dominance of the system transfer function matrix. Throughout the bandwidth the amplitude of the nutation response is at least 20 dB down on the amplitude of the precession response, compared with only 6 dB down on an uncompensated strapdown DTG. The compensator-strap down DTG system bandwidth is extended, compared to the strapdown DTG. The increase in bandwidth and improvement in system diagonal dominance depends on the precise form of the compensator and the manner of implementation; analogue, digital or hybrid. The compensator is feed-forward and can therefore be integrated into a system without altering the strapdown loops. The flexibility of the strategy enables the system designer to balance conflicting requirements of performance allied with minimal, cost, hardware and processing increases. An analogue and hybrid version of the compensator has been added to a strapdown DTG with subsequent test results in close agreement with theoretical studies. The control strategy has potential applications wherever strapdown DTG's are used.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Gyroscope dynamics Machinery Tools Physics