Inertial and RF sensor fusion
A method of determining the orientation of a device having disposed therein, in part, an inertia measurement unit, a phased array receiver, and a controller, includes, in part, detecting the difference between phases of an RF signal received by at least a pair of receive elements of the phased array receiver, determining the angle of incidence of the RF signal from the phase difference, using the angle of incidence to determine the projection of a vector on a plane of an array of transmitters transmitting the RF signal, and determining the yaw of the device from the projection of the vector. The vector is a three-dimensional vector representative of the orientation of the plane of the phased array receivers relative to the plane of the array of transmitters transmitting the RF signal.
1. A method of determining an orientation of a device comprising an inertia measurement unit, a phased array receiver, and a controller, the method comprising:
receiving an RF signal by at least first and second antennas of the phased array receiver;
detecting a difference between phases of the received RF signal;
determining an angle of incidence of the RF signal in accordance with the phase difference;
using the angle of incidence to determine a projection of a vector on a plane of an array of transmitters transmitting the RF signal, said vector being a three-dimensional vector representative of an orientation of a plane of the phased array receivers relative to a plane of the array of transmitters transmitting the RF signal; and
determining a yaw (φ yaw ) of the device from the projection of the vector.
2. The method of claim 1 wherein said vector comprises component values defined by the inertia measurement unit.
3. The method of claim 2 wherein said RF signal charges the device.
4. The method of claim 1 wherein the yaw is defined by:
φ
yaw
=
tan
-
1
(
b
y
b
x
)
,
where b y and b x are y and x components of the projection of said vector.
5. The method of claim 4 wherein said vector is defined by: b=(n×V beam )×n, wherein n is a unit vector perpendicular to the plane of the array of transmitters and V beam is a three-dimensional vector defining a degree of rotation of the device about three axis as supplied by the inertia measurement unit.
6. The method of claim 1 wherein said array of transmitters is a phased array transmitter.
7. The method of claim 1 wherein said vector comprises component values defined by a magnetic sensor.