TY - JOUR N2 - Rotation modulation can significantly improve the navigation accuracies of an inertial navigation system (INS) and a strap-down configuration dominating in this type of INS. However, this style of construction is not a good scheme since it has no servo loop to counteract a vehicle manoeuvre. This paper proposes a rotary upgrading method for a rotational INS based on an inertially stabilized platform. The servo control loop is reconstructed on a four-gimbal platform, and it has the functions of providing both a level stability relative to the navigation frame and an azimuth rotation at a speed of 1:2◦/s. With the platform’s rotation, the observability and the convergence speed of the estimation for the initial alignment can be improved, as well as the biases of the gyroscopes and accelerometers be modulated into zero-mean periodic values. An open-loop initial alignment method is designed, and its detailed algorithms are delivered. The experiment result shows that the newly designed rotational INS has reached an accuracy of 0.38 n mile/h (CEP, circular error probable). The feasibility and engineering applicability of the designed scheme have been validated. L1 - http://journals.pan.pl/Content/114019/PDF/03_MMS_4_INTERNET.pdf L2 - http://journals.pan.pl/Content/114019 PY - 2019 IS - No 4 EP - 629 DO - 10.24425/mms.2019.130566 KW - inertially stabilized platform (ISP) KW - rotation modulation KW - four-gimbal platform KW - servo control KW - initial alignment A1 - Guo, Rong A1 - Wang, Xueyun A1 - Zhang, Jingjuan A1 - Song, Tianxiao PB - Polish Academy of Sciences Committee on Metrology and Scientific Instrumentation VL - vol. 26 DA - 2019.12.28 T1 - Rotary upgrading method and its experimental study of an inertially stabilized platform SP - 617 UR - http://journals.pan.pl/dlibra/publication/edition/114019 T2 - Metrology and Measurement Systems ER -