Dynamic lever arm compensation of SINS/GPS integrated system for aerial mapping

Strapdown inertial navigation system (SINS)/global positioning system (GPS) integrated system is an important way of accurate measurement of the mapping sensors for high resolution aerial mapping. However, for keeping the mapping sensor level and appointed direction, inertially stabilized platform (ISP) will be applied and rotate its three gimbals. The lever arm between inertial measurement unit (IMU) and GPS antenna will be time-varying. Therefore, the precise compensation of the effect of the dynamic lever arm will be significant for the measurement accuracy of SINS/GPS integrated system. An algorithm which tackles the problem is proposed, the dynamic lever arm is originally considered as the summation of two relative constant lever arms. Then, with the aid of the encoder data of ISP, the algorithm of dynamic lever arm compensation is derived in the paper. As the nonlinearity of the system, the demand of the on-line and off-line processing, unscented Kalman filter and smoother for nonlinear estimation are applied. Finally, the proposed algorithm of dynamic lever arm compensation is applied to a flight data of aerial mapping experiment. It is shown from the experiment results that the proposed algorithm can more effectively compensate the degradation of the measurement information than the traditional algorithm.