Further Application of Pitch Independent Laser Doppler Velocimeter in Land Vehicle Autonomous Navigation

The strapdown inertial navigation system (SINS) and pitch-independent laser Doppler velocimeter (PI-LDV) integration represents a traditional navigation architecture. However, its effectiveness in obtaining precise altitude measurements remains constrained by the PI-LDV's inherent limitation of providing only one-dimensional velocity information. This study addresses this limitation by using the optical path structure of the PI-LDV to construct a frame capable of providing two-dimensional velocity information. To achieve this objective, two innovative integration methods are proposed: a SINS/PI-LDV loosely coupled integration method and a SINS/PI-LDV tightly coupled integration method, both of which consider the influence of potential laser beam fluctuations. Furthermore, a displacement increment measurement model is developed for the SINS/PI-LDV integrated navigation system to maximize the utilization efficiency of PI-LDV measurements while reducing the impact of sensor noise and outliers. The effectiveness of the proposed methods is rigorously validated through a comprehensive series of experimental tests, including: 1) extended-duration, long-distance tests using high-precision inertial measurement units (IMUs); 2) short-duration, limited-range evaluations using high-precision IMUs; and 3) two additional long-distance verification experiments using both high-precision and medium-precision IMUs. Experimental results demonstrate that the proposed method significantly outperforms traditional methods, particularly in height accuracy. Notably, the performance advantages become more pronounced when implementing the SINS/PI-LDV integrated navigation system with medium-precision IMUs, suggesting enhanced practical applicability in cost-sensitive applications.