H-infinity control of the NRC Bell 205 fly-by-wire helicopter

The design and flight-testing of a multivariable helicopter flight-control system is reported on. The design was based on H-infinity optimization and a low-order rigid-body model of the aircraft dynamics. The test-aircraft wa s a modified Bell 205. Evaluations were carried out at hover and low/modera te speed. The controller successfully engaged first time and provided adequ ate-to-desired (level 2) performance on a number of tasks. This is believed to be the first successful Right-test of an H-infinity optimal multivariab le controller on a rotorcraft. A summary of data gathered during over eight hours of test-flights, together with some handling qualities evaluation, i s presented.