The article discusses the development of algorithms for improving land mobile object autonomous navigation. The navigation can be performed using inertial navigation system (INS) operating all alone or using odometer complementary to INS. In the former case, accuracy is improved as a result of INS error correction conducted during periodic stops of the object. In the latter the accuracy improvement is a result of calibration of INS and odometer errors on the known coordinates of at least one route point. The advantage of the proposed methods is their principal autonomy: there is no need to transmit/receive any signal from outside for their implementation. In each situation under consideration the proposed algorithms can significantly increase the accuracy of determining the location and velocity of the moving object. The results of algorithm testing on the INS of middle accuracy rating mounted on the cross-country vehicle are presented.