Barometer error identification filter design using sigma point hypotheses

In many applications for air-vehicles flying in low altitude, it is very important to provide accurate height information steadily. Although barometers can provide the height measurements continuously, their errors tend to increase as the air-vehicle flies far from the launch point. To cope with the problem, another auxiliary altimeter such as GPS or radio altimeter can be adopted, but their performance and availability are very sensitive to the vehicle attitude and various jamming situations. In this paper, a new height sensing system combining these two kinds of sensors is suggested. In the system, the barometer errors are identified and compensated to steadily supply the accurate baro-altitude. For the identification, barometer error models are investigated and a new filtering method based on the zero-scan-back multiple hypothesis filtering concept is derived. For obtaining the computationally effective filter structure, some simplifications using the sigma point hypotheses are introduced. Simulation results show that the proposed filter can successfully estimate and compensate the baro-errors.