Accurate Sensing of Low Speed Vehicle Motion Relative to a Moving Platform

Unmanned aerial vehicles (UAVs), taxiing under their own power on the flight deck of a ship, may not always move in the direction commanded. Deck conditions, such as fluid on the deck or the ships rolling or pitching can cause aircraft skidding, sliding, or rearward movement. Such unwanted movement fails to register on aircraft pilot instruments. A remotely located UAV pilot needs the true direction and speed of motion relative to the deck displayed. This allows for detection of and reaction to sliding or skidding and/or to initiate appropriate emergency response if required. Skidding and sliding can have lateral as well as longitudinal velocity. A sensor suite is needed which will measure both longitudinal and lateral movement referenced to the deck and which can make these measurements for speeds as low as 0.4 mph. Mass produced very economical and rugged commercial-off-the-shelf 60-GHz radar modules measure such very slow lateral and longitudinal speed by scanning the deck. Speed measurements from two separate radar sensing techniques, Doppler and cross correlation, are presented to a Kalman tracker which heavily weights the more reliable measurement at that moment or carries on without sensor updates if sensor data is missing at that instant.