Solid state device for the measurement of light aircraft roll attitude

The authors describe a non-gyroscopic solid state device which provides an indication of the roll altitude of a light aircraft. The difference in altitude between the left and right wing tips is measured by commercially available solid state pressure sensors. For an average light aircraft with a wingspan of about 40 feet, the electrical signal corresponding to 1 degree in the roll attitude is of the order of 0.2 mV, but this measurement is also subject to ripple and drift noises of the same order of magnitude as the useful data. A microprocessor-based digital filter is described which cancels these effects and produces a reliable indication of roll attitude. The filtering philosophy uses an observation technique based on the dynamics of the lateral motion of the aircraft system. It is shown that even an approximate knowledge of the mathematical model results in effective filter operation and acceptable instrument fidelity