Abstract
In the mobile optoelectronic tracking system (MOTS) based on charge-coupled device (CCD) and fiber-optic gyroscope (FOG), the tracking performance (TP) and anti-disturbance ability (ADA) characterized by boresight error are of equal importance. Generally, the position tracking loop, limited by the image integration time of CCD, would be subject to a non-negligible delay and low-sampling rate, which could not minimize the boresight error. Although the FOG-based velocity loop could enhance the ADA of the system, it is still insufficient in the case of some uncertain disturbances. In this paper, a feedforward control method based on the results of error and disturbance observation was proposed. The error observer (EOB) based on the CCD data and model output essentially combined the low-frequency tracking feedforward and closed-loop disturbance observer (DOB), which could simultaneously enhance the low-frequency TP and ADA. In addition, in view of the poor low-frequency performance of the FOG due to drift and noise that may result in the inaccuracy of the observed low-frequency disturbance, the FOG-based DOB was used to improve the relatively high-frequency ADA. The proposed method could make EOB and DOB complementary and help to obtain a high-precision MOTS, for in practical engineering, we give more attention to the low-frequency TP and full-band ADA. Simulations and experiments demonstrated that the proposed method was valid and had a much better performance than the traditional velocity and position double-loop control (VPDC).
Highlights
The charge-coupled device (CCD)-based mobile optoelectronic tracking system (MOTS), commonly mounted on vehicles, ships, airplanes and satellites, is mainly used for astronomical observation, free space communication, searching and target tracking [1–5]
The light from the target could of Section is the experimental part, indicating the detailed improvement of the tracking performance (TP) and anti-disturbance ability (ADA)
To enhance the ADA, a fiber-optic gyroscope (FOG) was mounted on the lens barrel to measure disturbances
Summary
The charge-coupled device (CCD)-based mobile optoelectronic tracking system (MOTS), commonly mounted on vehicles, ships, airplanes and satellites, is mainly used for astronomical observation, free space communication, searching and target tracking [1–5]. The closed-loop control of the system is based on the boresight error detected by a CCD. An unconventional feedforward control method based on the error and disturbance observation was proposed considering the velocity and position double-loop control (VPDC). The CCD-based error observer (EOB) combined the differential of the boresight error and model output with a delay to generate a composite velocity, which simultaneously contained the delayed signals of the target motion and disturbance.
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