Analytical control synthesis for adaptive flying-qualities adherence

An analytical procedure is described for synthesis and stability assessment of control systems for adaptive flying-qualities adherence with linear and nonlinear aircraft dynamics. This procedure directly incorporates desired low-order equivalent system (LOES) frequency and damping parameter values into the synthesis of control laws that provide optimal adherence to MIL-STD-1797A guidelines. The procedure is used to derive a longitudinal control law for a contemporary fighter aircraft. Simulation results are presented. It is believed that this approach offers improved flying qualities and may be suitable for mitigation of pilot induced oscillation problems because its closed-loop phase lag is essentially that of the LOES specification.