Remarks on stability robustness of linear quadratic regulators

摘要

In Chen, Holohan (Int. J. Robust Nonlinear Control 2016; 26:1817-1824), it is discussed that the stability margins (based on the minimum singular value of the return difference) of linear quadratic regulators with a non-diagonal weight (not in the form of a constant multiple of identity matrix) on control input may be low. This note, however, points out that those low stability margins can easily be avoided by introducing scaling matrices around the link where the feedback loop is broken to evaluate the return difference.