Single GNSS Antenna Heading Estimation

Abstract

Heading is an important state in modern vehicle control, especially in applications like ships in currents, aircraft in crosswinds, helicopters or Vertical Take Off and Landing (VTOL) aircraft. And yet there is only limited means to measure a vehicle’s heading on earth, and each approach has its drawbacks and limitations. Magnetometers for example are susceptible to electromagnetic interference and are of limited use in polar regions. Alternatives such as gyrocompass systems or GNSS antenna arrays come with a significant price tag and / or complexity. This paper presents a heading estimation procedure using inexpensive hardware and without the limitations of a system based on measuring magnetic field strength: the combination of a single element Dual Polarization GNSS Antenna (DPA) that delivers a low frequency, low accuracy absolute heading measurement and a MEMS rate gyro. Both sensors are characterized, and their measurement models justified. Two algorithms are then described to fuse the measurements from both sensors in a Kalman Filter. Simulation results outline the technique’s performance, depending on the quality of the rate gyro used and the DPA’s measurement characteristics. Test results from a dynamic driving test compare the heading estimate using the current implementation of the DPA to the estimate based of a magnetometer combined with the same rate gyro. The DPA based result is comparable to the magnetometer-based result in heading rate, but shows lower accuracy in absolute heading. Pareto curves based on simulation results outline how this limitation could be overcome in the future.