  It is essential that a robot has the ability to determine its position and
orientation to execute tasks autonomously. Heading estimation is especially
challenging in indoor environments where magnetic distortions make
magnetometer-based heading estimation difficult. Ultra-wideband (UWB)
transceivers are common in indoor localization problems. This letter
experimentally demonstrates how to use UWB range and received signal strength
(RSS) measurements to estimate robot heading. The RSS of a UWB antenna varies
with its orientation. As such, a Gaussian process (GP) is used to learn a
data-driven relationship from UWB range and RSS inputs to orientation outputs.
Combined with a gyroscope in an invariant extended Kalman filter, this realizes
a heading estimation method that uses only UWB and gyroscope measurements.
