Relative Ultra Tight IMU/GPS Integration

Intelligent Automation Inc. (IAI) proposes a novel ultra tightly integrated IMU/GPS system where two or more integrated IMU/GPS units send their raw observation as well as IMU measurements for relative positioning. In this proposed method we develop a new GPS receiver based on IAI’s Cooperative RAKE receiver that is capable of significantly reducing the effect of multipath induced error by tracking each discernable multipath and line of sight signal on each RAKE finger independently. In addition to this, the integrated IMU/GPS algorithm uses the PLL tracking loop to generate and track GPS signal. Once a GPS satellite (channel) is lost this generated GPS signal will be used as the input to the receiver so that the PLL continuously track the lost channel. This allows a very narrowband filter for the PLL with very fast carrier recovery and tracking when the lost channel is regained. Even in the case of total GPS blackout a high accuracy IMU is used for generating GPS signal for the input of the receiver for an interval of time which depends on the performance of the IMU.