Wide-envelope control of a battlefield helicopter

Full envelope active control of helicopters is a challenging problem characterised by high degrees of coupling, varying dynamics with flight condition, plus the requirement for completely different control strategies at either end of the speed range. This paper presents a case study of a wide-envelope design for such a system, based on mixed sensitivity H_∞ optimisation. A scheduled control scheme is been developed which achieves high levels of decoupling, attains a smooth transition between attitude and rate command schemes, and goes a long way to satisfying current handling qualities requirements