Adaptive stabilisation of lateral motion of a balloon gondola

Abstract Two approaches to adaptive stabilisation of the undesired lateral motion of the balloon gondola (theadaptive notch filter and the adaptive Butterworth filter which controls the phase of undesired oscillations) are reviewed, demonstrated and compared by simulations and laboratory experiments. This undesired motion is caused by asymmetric loading of the gondola, and is sensed by a simple magnetic sensor due to the vertical component of the earth's magnetic field. With the adaptive Butterworth filter a technique similar to Nussbaum's controller for the global stabilisation of adaptive systems with unknown high-frequency gains is proposed and used to stabilise the closed-loop system.