An analysis of the destabilizing effect of daisy chained rate-limited actuators

The response of a rate-limited actuator will lag behind a rapidly changing command. This lag may destabilize the closed-loop system. When multiple actuators are arranged in a daisy chain this effect can be significantly worse. The cost of daisy chaining, in terms of lost stability margin, is estimated analytically and numerically. A comparison of a simple daisy chain with a simple "cooperative" control selector shows that the daisy chain may cause as much as 30/spl deg/ of additional phase lag.