Discussion of “On adaptive control systems”

The system described by Braun is similar in philosophy to the system described by Mishkin and Haddad. In the latter, an attempt was made to drive the error and its derivatives approximately to zero by the end of each control interval. In the system of Braun, it appears the error and its derivatives are to go instantly to zero at the start of each control interval and to remain approximately zero for the duration of the control interval. This is physically impossible in any real system. That is, with finite power we cannot achieve instantaneous change in the output.