The use of walsh functions in multivariable limit cycle prediction

The describing function method has played a leading role in the prediction of limit cycles in scalar systems; in recent years this approach has been extended to the multivariable case. Derived techniques assume the nonlinearity inputs to be sinusoidal. However, this condition is not always satisfied, and as an alternative, the present paper considers the use of a method which is based on a set of non-sinusoidal functions. Novel concepts related to the characteristic loci are defined and employed for the derivation of new graphical tests.