Phase Compensated Rate Limiters for Alleviation of Pilot-Induced Oscillations Caused by Control Surface Rate Limiting

The basic characteristics of Phase Compensated Rate Limiters, PCRL’s, are explained and their application to the alleviation of Pilot-Induced Oscillations, PIO, caused by control surface actuator rate limiting is demonstrated.

It is shown that PCRL’s can recover a large percentage of the control system phase loss caused by surface rate limiting while maintaining minimal temporary bias in the control surface response following rapid command reversals.

Their superior performance in meeting PIO criteria is shown by comparing the simulation results from an extensive study that was aimed at finding solutions for alleviating roll-axis PIO on an airplane where aileron and spoiler surface rate limiting appeared to be a predominant causal factor.

A comprehensive investigation of the effect of rate limiting in pilot-induced –oscillations is reported in Ref. 2