A Cold-Atom Strapdown Inertial Unit Guided by the Transit Law

Inertial navigation integrates acceleration and rotation into position, and its accuracy is the accuracy of its sensors' biases. Atom interferometers measure both quantities against atomic constants, with biases that do not drift like those of mechanical or optical gyroscopes. This paper designs a strapdown cold-atom inertial unit and computes its sensitivity. With an interrogation time of 0.25 s and an atom flux of one million per shot, the acceleration sensitivity is 0.1 microgal per root hertz and the rotation sensitivity 9.94e-08 rad per second per root hertz. A transit-law scheduling scheme sequences the unit's measurements along the trajectory so that bias estimation and map aiding combine optimally. The unit is a simulated design; no atoms were interfered in its preparation.