lassification is recommended The driven machine B2-SV-9-A Bevel-helical gear reducers B2

Flender/Flender Gear Units/Bevel-helical gear reducers B2

line represents GMM with 2 components which have unconstrained covariance matrices, and the dash-dotted line (which closely corresponds to the dashed line) represents NLL values as conditioned on the pinion shaft angular velocity ln[(si;ci)=(ci)]. () The NLL of the operating conditions ln [(ci)]. GMM density distribution is used to represent the signal segments which correspond to the fault free data. The vibration signal is sampled at 1k datum points per rotation of the pinion. Since there are 2 teeth on the pinion the signal segments have length of 5 data points. The window length of 5 data points results in GMM with many free parameters. In general it might be benecial to consider down sampling the vibration signal so that smaller GMM may be implemented. Alternatively it may also be considered to extract and model subset of features (.. through principal component, or wavelet analysis). Lastly may it also be considered to constrain the covariance matrices, for instance by implementing diagonal covariance matrices. Three approaches are investigated towards implementing the proposed strategy. The GMMs are implemented on vibration signals which were subject to random noise. noise standard deviation of =0:2 is implemented. This noise level renders it completely impossible to identify the faulty gear tooth by means of conventional synchronous averaging. The rst approach is implemented by using GMM with constrained covariance matrices. diagonal covariance matrix is not capable of modelling the covariance between different datum points, but is also less prone to overt data. GMMs with different numbers of mixture components are investigated. It is found that single component with constrained diagonal covariance is especially poor at discerning between time-varying operating conditions and fault induced signal outliers. Performance is signicantly improved by implementing 2 components, but it is found that at least 1 components are required to obtain results whi