Frequency response function measurement and parametric SISO system modelling of a gyro-stabilized infrared electro optic gimbal system

In this research study, a single axis (inner azimuth gimbal) of a four-axis gyro-stabilized electro optic gimbal system is modelled through experimental investigation in the frequency domain, and the results of this investigation are presented. The dynamic behaviour of the mechanical system is obtained from input and output signals, strictly speaking, nonparametric measurements. Detecting and measuring the nonlinear distortions allows a better understanding and gives an intuitive insight into the error sources on frequency response function measurements. In this study, a nonparametric frequency response function and its uncertainty (noise) are measured; nonlinear distortions are quantified on a real-time system. The dynamic system is modelled by its parametric transfer function with various different estimation techniques and their efficiencies, convergence properties, and bias errors are compared and discussed. It turns out that, the nonparametric noise model allows the estimator to weight the cost function and reach statistically better results. As an original contribution, a common problem encountered with gimbals having small rotational movement capacity (in this case study, +/- 5 degrees for the inner gimbals) is formulated as an optimization problem. An optimization procedure is studied to achieve a better signal-to-noise ratio in the frequency band of interest, while satisfying device-specific constraints.


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In this work, two novel nonlinear system identification methods are proposed in both the modal and spatial domains, respectively, based on response-controlled stepped-sine testing (RCT) where the displacement amplitude of the excitation point is kept constant throughout the frequency sweep. The proposed nonlinear modal identification method, which is also a nonlinear experimental modal analysis technique, applies to systems with several nonlinearities at different (and even unknown) locations (e.g. joint no...
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In this thesis, nonlinear vibration analysis of both fixed L-shaped beam and L-shaped beam attached to a single degree of freedom (SDOF) system is performed for several cases with different structural parameters to observe the effect of these parameters. Then these beams are proposed to reduce the vibration amplitudes of certain structures, and the nonlinear effects on the dynamic responses of these structures are investigated. The nonlinear dynamic model of the L-shaped beam is obtained by using Euler-Bern...
Citation Formats
G. Ozdogan and M. K. Leblebicioğlu, “Frequency response function measurement and parametric SISO system modelling of a gyro-stabilized infrared electro optic gimbal system,” TRANSACTIONS OF THE INSTITUTE OF MEASUREMENT AND CONTROL, pp. 512–528, 2016, Accessed: 00, 2020. [Online]. Available: