Removal of the rate table:MEMS gyrocompass with virtual maytagging

High-performance micro-electro-mechanical system(MEMS)gyrocompasses for north-finding systems have been very popular for decades.In this paper,a MEMS north-finding system(NFS)based on virtual maytagging(VM)is presented for the first time.In stark contrast to previous schemes of MEMS-based NFSs(e.g.,carouseling,maytagging)and the abandoning rate table,we developed a honeycomb disk resonator gyroscope(HDRG)and two commercial accelerometers for azimuth detection.Instead of the physical rotation of the integrated turntable in traditional NFSs,the vibratory working modes of the HDRG are rotated periodically with electronic control to reduce the uncertainty in the azimuth.After systematically analyzing the principle of NFSs with VM,we designed tests to verify the practicability at the sensor level.A bias instability of 0.0078°/h can be obtained during one day with VM in an HDRG.We also implemented comparative north-finding experiments to further check our strategy at the system level.The accuracy in the azimuth can reach 0.204°for 5 min at 28.2°latitude with VM and 0.172°with maytagging.The results show that without any mechanical turning parts,VM technology makes it possible to develop high-precision handheld MEMS NFSs.