Research And Implementation Of Testing Method For Resonant Frequency On Precision Servo Mechanism

Resonance frequency is a parameter that has important effect on dynamic properties of servo mechanism. In this thesis, an infrared seeker of servo mechanism is set as measured object. Further, the design and development process of precision servo resonance frequency of test system is discussed and key techniques in design are also researched.Firstly, the mathematical modeling of servo mechanism is finished. Secondly, by analyzing and discussing relevant influence factors of servo resonance frequency, such as the cause of this frequency, the influence on mechanism performance and inhibition method and so on, the advantages and disadvantages of different test methods have been found. After comparing characters of each test methods, sine point frequency sweep test method is adopted in this thesis.The overall plan of test system is designed by special selection of key electrical parts.Secondly, this thesis not only introduces the hardware design scheme in detail, but also describes the layout construction of core parts, such as control panel, RDC spin variable decoding board and power amplifier drive plate. Concretely speaking, control panel consists of communication circuit, interface circuit, high-precision DA output circuit and power management circuit, but its core part is DSP+FPGA; RDC spin variable board includes core decoding chip, 32-bit DDS excitation circuit, CPLD configuration circuit and all levels of filter circuit and parameter setting circuit parts. In addition, aiming at each circuit board characteristics, appropriate measures are adopted to improve signal performance index, such as completeness, anti-interference performance and so on.Thirdly, according to demands of observation and control technology, this thesis describes the design plan of software system in detail. The software system has two work patterns. The first pattern can realize precise point to action of double loop PID control servo. The second pattern can conduct sine sweep frequency point by point after interrupting position loop and speed loop. Besides the pattern function introduced above, the two work patterns can also design and achieve module initialization, upper machine communication and real-time speed acquisition. At the same time, this thesis intersperses with programming tricks of DSP and FPGA, such as multiplexed expansion bus, state machine, ping pong operation technology and so on, which has been introduced in engineering experience aspect specifically.Finally, this thesis emphatically discusses the adjustment processes and shows the experimental results of hardware system of each version, which are based on measured object of infrared seeker servo mechanism. By drawing the amplitude frequency and phase frequency curves, the mechanical resonance frequency is obtained, which verifies that the design of this system is correct.