Jitter Measurement Of The Large Telescope Axis

With the delelopment of space exploration, the requirement of large aperturetelescope tracking accuracy is more and more high. The jitter of telescope system cancause visual axis deviation, deduce tracing accuracy and blur images. In order toachieve high precision tracking and reduce the system error,we need to measure andevaluate the system jitter.Firstly, we describe the demand analysis of jitter measurement, and design theoverall plan of system, including measuring tool selection and the core controller ofdata acquisition system selection. We describe the linear accelerometer’s measuringprinciple and specification parameters in detail. Also, we describe the function of dataacquisition system and select DSP as the core controller, combined with CPLD tocomplete data acquisition task.Secondly, we describe the hardware design and software design of dataacquisition system. The hardware circuit is divided into the accelerometer outputsignal conditioning circuit and data acquisition circuit. The circuit diagrams of eachfunction module are given with a description of their working principle. The softwaredesign includes the DSP main program and the CPLD program, the main functionmodule is described. We make a simulation for CPLD program, the timing can meetthe requirement. Also we debug the whole system, the results show that the design ofdata acquisition system can complete the task of jitter acquisition.Thirdly, we study the application of digital signal processing technology in jitterdata processing. A detailed analysis of the principle of wavelet denoising technologyis given, and the algorithm is validated by simulation. We describe the powerspectrum estimation method in detail, and the different power spectrum estimationmethods are compared by a simulation.Finally, we set up the jitter measurement system based on small turntable and 1.23m telescope, and complete the experiment. The results show that the positionjitter in1.23m telescope axis can keep below0.4arcsec. The experiments prove thefeasibility of jitter measurement method in large telescope. According to the methodof measuring acceleration, we put forward a method to reduce the jitter disturbance.The method is joining the acceleration negative feedback in the DC motor controlsystem. The simulation results show that, the system with acceleration feedback canimprove the ability of depressing disturbance.