The electro-optical tracking system with the capability of target capture and tracking, is typical astronomical observation instruments. In most of the task scenarios, the electro-optical tracking system must finish the azimuth zero calibration at the initial stage. Two methods are usually used for zero calibration: (1) with the aid of the external autonomous north seeking equipment; (2) with the help of the astronomical measurements under clear weather. The former problem is the increased cost for purchasing additional equipment and training operators, while the latter is limited by weather conditions and personnel experience. In this paper, an independent azimuth zero calibration method based on single gyro for electro-optical tracking system is proposed, which introduces a four-position method on the basis of high-precision angle measure sensor and gyro equipped in the system to calibrate azimuth zero point. The all-weather independent azimuth zero calibration is realized, after data sampling and processing. The experimental verification results illustrate the azimuth zero calibration precision is less than 3’ in 4 minutes, meeting the initial zero calibration requirements of electro-optical tracking system.
To improve the optoelectronic tracking ability and rope-hanged platform attitude stability, against the interact effect
between rope-hanged platform and optoelectronic system during system tracking process, the optoelectronic system
fixed on rope hanged platform simplified dynamic model, according to the system’s Lagrange dynamic model, was
established. Backstepping method was employed to design an integrated controller for both optoelectronic system
azimuth direction steering and platform attitude stabilizing. To deal with model’s uncertainty and disturbance, a sliding mode controller form based exponential reaching law was adopted to structure the integrated controller. Simulation experiments simulated an optoelectronic system with 600mm caliber telescope, whose inertia fluctuation is 6%. The maximal control moment is 15Nm. And the external disturbance and internal friction effected together. When the line of sight(LOS) azimuth angular input is a step signal with 1rad amplitude, the response’s overshoot is 6%, and the response time is 6.2s, and the steady state error is less than 4×10-4rad. When the input is a sinusoidal signal of 0.2rad amplitude with 0.0318Hz frequency, the LOS azimuth angular error amplitude is 5. 6×10-4rad. It is concluded that the controller designed in this article has excellent ability and can ensure the system’s stability.
Two common structures were often adopted to construct the photoelectric system that fixed on soft-rope hanged
platform. Both of the horizontal photoelectric system and X-Y
Double-Axis Gimbal photoelectric system have blind
regions, so they have different application. This article regarded the photoelectric system fixed on soft-rope hanged
platform as multi-rigid-body system. Lagrange equation and augmented body theory were employed to establish the
balloon borne photoelectric system's dynamic model as torques that imposed on the photoelectric system were
considered. Channel matrix and matrix of constraint force element and some other matrixes were used to describe the
photoelectric system's dynamics. Numerical simulations have been performed to compare the two kinds of balloonborne
photoelectric system's performance. According to simulation result, different application situation were given for
the two structure photoelectric systems fixed on rope hanged platform. The x-y double-axis photoelectric system is
adequate for tracking high-elevation object, and has better stabilization ability against pendulum disturbance. The
horizontal photoelectric system was good at tracking low-elevation object and has better ability to eliminate twist torque.
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