Incipient Gearbox Fault Diagnosis Based on the Reverse State Transformation of the Chaotic Duffing Oscillator and Sampling Integral Technology

Figure 9

The movement of both the phase portrait of Duffing system with input detected signal and the first feature of moment invariants.

(a) Phase portrait of Duffing system on criticality state and the first feature of moment invariants is 0.1972

(b) The phase portrait of Duffing system with input detected signal and the first feature of moment invariants is 0.1775

(c) The phase portrait of Duffing system on criticality state with input detected signal and the first feature of moment invariants is 0.1962

(d) The phase portrait of Duffing system with input detected signal and the first feature of moment invariants is 0.1825