Accuracy requirements of nonlinear compensation for backlash

Recent advances in the analysis of nonlinear control systems have given rise to a more logical and systematic approach to the elimination of the detrimental effects of inherent nonlinearities. The describing function technique is used in this paper to analyze two typical servos. The servos are shown to exhibit a stable limit cycle and are stabilized by linear and nonlinear techniques. The nonlinear technique involves the insertion of an additional nonlinear feedback element which feeds back a distorted signal opposite in phase to the original distorted feedback signal. In particular, a method is developed in this paper for determining the accuracy required in the construction of a practical nonlinear compensating element.