Parameter-Adaptive Model-Following for In-Flight Simulation

In-flight simulat.ions are normally accomplished by using control laws which depend on accurate knowledge of the stability derivatives of the host aircraft. Degraded performance may result if the stability derivatives deviate considerably from their presumed values. Gain scheduling can compensate for parameter variations, but this form of open-loop compensation m y require extensive flight testing for fine tuning. This paper implements an adaptIve mntrol law to compensate for changing aircraft parameters. The step-response matrix required by 'the control law 1s identified recursively using a recently developed technique which does not requ'ire special "test" signals and which discounts old data depending on the input excitation detected. Tracking fidelity i s maintained despite parameter changes. The control design package MATRIXx is used to test the adapttve system. The performance of the resulting system i s excel lent and demonstrates the relative advantages of adaptive controlliers for in-flight simulation.