Study On Strength And Dynamics Of Seeker Servo Mechanism

Seeker system, which can possess some functions such as capture, tracking, aiming and stabilization, is applied to the precision guided weapon widely. As an important part of seeker system, seeker servo mechanism can provide inertia stabilized platform for photoelectric detector, and its structural performance has a direct effect on the performance of seeker system. With the improvement of the flight speed and guidance precision of the final guidance supersonic missile, operating condition in missile is worse and worse, and the newer demands is put forward for the strength design and the dynamics analysis of servo mechanism. So it is very urgent that the strength design methods and the influence mechanism of dynamics of the high precision lightweighting servo mechanism are researched in depth. Under this circumstance, this dissertation suggests two research aspects included strength and dynamics, namely study on the guide lines and the high performance calculation methods of strength design when complicated dynamic load and study on the influence of structural parameters on dynamics. These studies can provide the foundations for the optimum design of the structure and control of the new-style seeker servo mechanism.The detailed contents and innovative work are organized as follows:1. In the structural strength respect, the traditional design methods are complex and low performance. In order to improve the performance of the strength design, computing methods, software realization and technical application problems are researched with parallel computing.Firstly, on the basis of finite element EBE parallel policy, finite element N-EBE-PCG parallel algorithm is presented and realized to calculate the structural response when deterministic load. Ulteriorly, combining N-EBE-PCG algorithm with pseudo excitation method, parallel pseudo excitation method is presented to calculate the structural response when stochastic load. The research and realization of the strength parallel algorithms is of advantage to improve the efficiency of the structural strength analysis when complicated dynamic load.Under the cluster of workstation (COW) environment, the strength parallel algorithms are applied to develop the strength parallel computing home-code based on the parallel programming mode of Message Passing Interface (MPI). In order to make these parallel algorithms take the form of software, the strength parallel computing home-code is integrated into ANSYS software seamlessly with the use of ANSYS Parameter Design Language (APDL).The dynamic environments which seeker servo mechanism suffers in its enlistment are analyzed systematically. And then, the strength parallel computing program is applied to calculate the mechanical strength of the inner and outer framework of a typical servo mechanism respectively under the shock and random vibration environments. Also, the strength sensitivity of structural design parameters is analyzed. It shows by simulation that the strength parallel computing program proposed has a high calculation precision and efficiency, and is applicable for the structural strength optimum design of the seeker servo mechanism under the complicated dynamic environments.2. In the dynamics respect, the traditional research of servo dynamics uses the ideal model and seldom allows for the random factors such as design tolerance, mismatchining tolerance and wear. So it can not describe the actual dynamics correctly. Therefor, the dynamic models with random factors which can describe the influence mechanism of dynamics better are researched based on the stochastic analysis methods.Firstly, the dynamic simulation model of the seeker servo mechanism is established based on the Hamilton mechanics principles and the influences of friction, nonlinear coupling and energy dissipation on the servo dynamic characteristics are analyzed. On the basis of the dynamic model, the random factors which affect the driving moment and inner friction of the servo mechanism are illuminated in full length according to the correlative experimental results, and the processing methods for these random factors are proposed.In order to analyze and evaluate the random response characteristic of the servo mechanism affected by the random excitation, the stochastic averaging methods of quasi Hamiltonian systems are investigated, and the points interpolation meshless (PIM) methods are studied to solve the FPK (Fokker-Planck-Kolmogorov) equations of stochastic dynamics. Following that, the random response of the servo mechanism is solved by the stochastic averaging methods and the the PIM methods. And then, the influence of the structural parameters on the stochastic response characteristic is studied. This work can provide theory foundations for evulating the dynamics of the mechanism.Aiming at the problem of the random friction, the mechanism and the calculation methods of the friction torque are studied systematically based on the basic theory of rolling bearing. Using these methods, the influence of the structural parameters on the dynamics is investigated in the Monte Carlo simulation test. This work makes preparations for the farther study on the evolvement rules of the servo dynamics.In a word, the parallel analysis technique of structural strength and the simulation method of nonlinear stochastic dynamics which are studied in this dissertation can be applicable for the optimum design of the servo structure and control.