To weaken the influence of constant bias of inertial components on navigation precision of strap-down inertial navigation system (SINS), the error modulation method which utilizes the IMU four-position indexing is proposed in this paper. In addition, the main error source (constant drift of gyro and zero bias of accelerometer) of single axis rotating system is mainly analysed. In this new scheme, the errors of inertial sensors are modulated into periodically varied signal, as a result, the divergence of SINS errors is suppressed in long time operation. The navigation error is compared with no rotary manner via simulation. Analyses and simulation test show that the effect of the constant bias of sensors can be eliminated effectively, thus the accuracy of attitude and positioning can be greatly enhanced.

No abstract

A pipe structure model composed of straight pipe, bent pipe, concentrated mass and flexible support was established. The axial, lateral and circumferential vibration of this model were taken into account in the paper. Then it was realized to calculate the natural characteristic of this pipeline in computer by using MATLAB language to program a series of procedures based on frequency-domain transfer matrix method. The calculation results were compared with the ANSYS simulation results, which illustrated the upper accuracy of frequency-domain transfer matrix method in calculating natural characteristic problems of pipeline structure system. At last, The pipeline system was analyzed with experimental modal method．By comparing the experimental results and computational results, relatively lesser error showed that computational results were reliable and frequency-domain TMM was verified to be valuable for practical application.

Considering the complex of space environment, the influence of flexible attachments, the restraint of measurement and control precision, it makes difficult to control the attitude precisely. In order to improve the attitude maneuver's rapidity and its stability, this paper studied the attitude maneuver's path programming method of satellite with the flexible attachments. Through the establishment of the dynamic model of flexible satellites, and using multi-objective optimization algorithm to select the optimal parameter, an asymmetric sinusoidal maneuver path was planned. Simulation results show that the planned path could suppress flexible appendages vibration which brought by attitude changes, then the effectiveness of the planning algorithm is demonstrated.

With the rotation modulation, a strapdown inertial navigation system (INS) can keep high accuracy navigation without high accuracy gyro and high accuracy accelerometer. Firstly we give the error equation of strapdown INS, and then deduct the navigation error propagation of system. From partial analysis way, the modulation process of gyro constant error is obtained. Form global analysis way, the navigation error roused by constant error and the modulation effects are deducted here.