Heading reference and land navigation system

摘要

A heading reference system (100) for sensing vehicle heading relative to fixed inertial space is mountable in a vehicle such as a land-based vehicle and includes a two-degree-of-freedom (TDF) dynamically tuned gyroscope (150) responsive to vehicle rotation about pitch and yaw axes for generating rate signals indicative of the rotation. A caging loop (160) generates force signals for torquing the gyroscope (150) to a null position. A pair of accelerometers (186, 187) are responsive to misalignment of the vehicle relative to a horizontal plane formed by the pitch and roll axes. Processor circuitry (180) is responsive to the force signals, the misalignment of the vehicle relative to pitch and roll axes, and distance signals generated by an odometer unit (140) to apply heading signals to an indicator unit (120) for visually indicating to a vehicle operator the directional heading.