Real-time inertial navigation systems should be initialized to provide an initial position, velocity, and attitude at start up prior to integration of inertial sensor data. An integrated navigation system can use non-inertial sources (also referred to herein as aiding sources) to provide this initial position, velocity, and attitude information. Example aiding sources can include a master navigation system, GPS receiver, barometric altimeter, magnetometers, and others.
Aiding source data is typically delayed in time (e.g., latent) by the time the navigation system can use the information. The aiding source data can be latent due to limitations in hardware and software such as digital update rates, available computational resources, interface message transmission and reception limitations, and other reasons. The latency of this data can introduce errors into a navigation solution if the latency is not accounted for when the data is used for initialization of the navigation system.
The errors introduced will depend on the dynamics of the body in which the inertial navigation system is associated. For example, for a vehicle traveling at 100 meters/second a 1 second delay in the aiding source data will introduce a 100 meter position error for the initialization of the inertial navigation system. Vehicle acceleration dynamics can introduce velocity error and vehicle angular rate dynamics can introduce attitude error. The greater the vehicle dynamics, the larger the errors for a given time delay.