Approach to fault detection of time-delay systems using functional observers

A new methodology is reported for designing functional observers to detect actuator faults of a class of time-delay systems where the matrix pair (A, C) is not observable. First, a generalised state transformation is used to transform the system into new coordinates where the delay term associated with the state vector is injected into the system's output and input. Then, a minimum-order functional observer is designed to construct a residual function that can trigger system faults. The finding is significant as it is now possible to detect faults of time-delay systems where the pair (A, C) is not required to be observable. A numerical example is given to illustrate the effectiveness of the proposed design approach. © The Institution of Engineering and Technology 2014.

Mobility of people with retinitis pigmentosa as a function of vision and psychological variables

We investigated the mobility performance of subjects with retinitis pigmentosa (RP) as a function of clinical measures of residual vision and psychological variables. We found a highly significant correlation between clinical measures of residual vision and mobility. Pelli-Robson contrast sensitivity and residual visual field together explained 64% of the variance in mobility performance in an indoor shopping mall. We suggest a simple new clinical method of scoring the visual field for predicting mobility performance, the RP Concentric Field Rating. The RP Concentric Field Rating alone explained 60% of the variance in mobility performance. In spite of expectations derived from reading the recent literature, we did not find a significant correlation between psychological variables and mobility performance in a group of subjects with RP.