Evaluation and design of actuator fault diagnosability for nonlinear affine uncertain systems with unknown indeterminate inputs

Summary In this paper, the evaluation and design scheme of fault diagnosability are investigated by differential geometry theories for a class of nonlinear affine uncertain systems with unknown indeterminate inputs. Considering two coupling relationships of outputs with uncertainties and faults, the sufficient and necessary conditions of fault detectability and isolability are established. For the problem that uncertainties influence the system outputs and make the faults undetectable, a design scheme of fault diagnosability is proposed. For nonlinear affine uncertain systems, a relatively complete theoretical system of the evaluation and design of fault diagnosability comes into being. An illustrative example is given to demonstrate the effectiveness of the proposed evaluation and design scheme of fault diagnosability. Copyright © 2016 John Wiley & Sons, Ltd.