Study on parasitical loop of GPS/INS lever effect

To study the influence of GPS/INS lever effect on guidance system, the principle of lever effect error caused by GPS/INS displaced from the gravity center of missile and its influence on the accuracy of line-of-sight angle rate were analyzed. The concept of lever-effect parasitical loop was presented. The model was constructed and converted to be dimensionless. According to different installation positions of GPS/INS, the stability of lever-effect parasitical loop and its influence on the performance of guidance loop were analyzed. With the decrease of missile-target distance, the stability of parasitical loop becomes worse. While GPS/INS is placed in the tail of missile, the lever effect is equivalent to a positive feedback, and the stability zone of the parasitical loop is minimal at this moment. The guidance accuracy is decreased also. The GPS/INS should be placed near to gravity center or at the fore of gravity center, and the lever effect should be compensated in the algorithm of integrated navigation.