In this paper, a friction compensating method based on data fusion in telescope controller is proposed to enhance the tracking precision of telescope systems. Telescope systems usually suffer some uncertain disturbances, such as friction, wind loads and other unknown disturbances. Especially, when telescope change speed direction, the friction is the dominate track error. Thereby, to ensure the tracking precision, the friction compensating method which can attenuate the influence of friction is introduced. Besides, to improve the friction identify accuracy, a data fusion method which fuse accelerometer and encoder is adopted. Finally, a few comparative experimental results show that the proposed control method has excellent performance for reducing the tracking error of telescope system.
In this paper, a method of acquisition between optical ground station and quantum communication satellite named Micius for establish optical links is proposed. The acquisition technological specification of the optical ground station system is analyzed. The acquisition strategy of optical ground station is designed. In order to point accurately to quantum satellite for optical ground station, system error modifying method is designed, using the telescope mount model to improve the absolute pointing precision. Finally the experiment result is proposed. Results show that the correction accuracy is better than 5μrad. The acquisition time is less than 5 seconds.
For large-aperture optical telescope, compared with the performance of azimuth in the control system, arc second-level
jitters exist in elevation under different speeds' working mode, especially low-speed working mode in the process of its
acquisition, tracking and pointing. The jitters are closely related to the working speed of the elevation, resulting in the
reduction of accuracy and low-speed stability of the telescope. By collecting a large number of measured data to the
elevation, we do analysis on jitters in the time domain, frequency domain and space domain respectively. And the
relation between jitter points and the leading speed of elevation and the corresponding space angle is concluded that the
jitters perform as periodic disturbance in space domain and the period of the corresponding space angle of the jitter
points is 79.1″ approximately. Then we did simulation, analysis and comparison to the influence of the
disturbance sources, like PWM power level output disturbance, torque (acceleration) disturbance, speed feedback
disturbance and position feedback disturbance on the elevation to find that the space periodic disturbance still exist in the
elevation performance. It leads us to infer that the problems maybe exist in angle measurement unit. The telescope
employs a 24-bit photoelectric encoder and we can calculate the encoder grating angular resolution as 79.1016'', which is
as the corresponding angle value in the whole encoder system of one period of the subdivision signal. The value is
approximately equal to the space frequency of the jitters. Therefore, the working elevation of the telescope is affected by
subdivision errors and the period of the subdivision error is identical to the period of encoder grating angular. Through
comprehensive consideration and mathematical analysis, that DC subdivision error of subdivision error sources causes
the jitters is determined, which is verified in the practical engineering. The method that analyze error sources from time
domain, frequency domain and space domain respectively has a very good role in guiding to find disturbance sources for
large-aperture optical telescope.
Fast steering mirror (FSM) is one of the most important components in electro-optical tracking system and access to FSM model is the basis for controlling and fault diagnosis. This paper presented a correlation identification method based on Invert-Repeated m-sequence which can be used in the electro-optical tracking system to achieve the model of FSM under low sampling rate. Firstly, this article discussed the properties of the Invert-Repeated m-sequence and program implemented in matlab language, then analyzed the principle of correlation identification method based on Invert-Repeated m-sequence by utilizing Wiener-Hopf equation which is simple to achieve with strong anti-jamming capability and small perturbations on the system. Finally, a FSM model with the experiment data got by Dynamic Signal Analyzer was built in Matlab/Simulink and identified by the method mentioned in the paper. The experiment showed that correlation identification method which has certain actual application value, based on Invert-Repeated m-sequence can obtain more accurate recognition results even if the FSM system’s output signal contained large variance noise.
A 19 element segmented MEMS deformable mirror(DM) based on electrostatic repulsive-force actuator is proposed and
fabricated using a commercial surface micromachining process PolyMUMPs. Impacts of different sizes of actuator on
DM’s characterizations such as stroke, work bandwidth, driving voltage and fill factor are analyzed and optimized. An
analytical analysis combined numerical simulation has been performed on the deformation of repulsive flexural beam
actuator regarding actuator size and boundary condition. These analytic insights could provide guidelines for future
MEMS DMs optimum design. A maximum stroke of the fabricated DM is 2.6μm, is larger than 2μm for the sacrificial
layer thickness of PolyMUMPs. The preliminary aberration correction of the whole DM array is also analyzed.
Compared to conventional MEMS DMs, this design demonstrates the advantage of large stroke over a standard surface
micromachining fabrication process with a thin deposited layer, and it would expand the application of MEMS DMs in