Abstract
The optimization of test node selection is key stage for analog circuits test modes. In this master thesis, optimization technique was studied for test node selection based on Ants Colony Algorithms. The studied technique can yield high faults detection and isolation rates with less number of nodes. The methods, used to select test nodes for fault isolation, such as Heuristic method, Ambiguity sets method and Hashing Method were discussed. The studied concepts can also be applied in the domain of fault dictionary approach for optimization purposes.
In the ACA proposed in this thesis, the objective function consists of the fault detection rate defined as the number of faults detected divided by the total number of faults times hundred per cent, and the fault isolation rate which is equal to the number of faults isolated divided by the number of fault detected times hundred percent. The transfer probability, also regarded as the rate of change of positions, is equal to the exponential power of -d , where d is the difference between two points located in a two dimensional space.
The updating procedure measures each solution against the last N solutions globally made by ACA. As soon as N solutions are available, their moving average X is computed; each new solution G is compared with X. If G value is lower than X value, the trail level of the last solution's moves is increased, otherwise it is decreased.
In this thesis, the efficiency of ACA-based technique was proved theoretically and by means of simulation. The source code, proving the suitability of ACA, was developed and run using the Matlab. The both fault detection and isolation rates were compared not only with the case where all the nodes were selected but also with the rates generated by the AdvancedSCH platform which is developed by our research team. The comparison shows that ACA-based technique best suits for test node selection.
Keywords: Fault Dictionary, Ant Colony Algorithms, Test Node Selection, Fault detection rate, Fault isolation rate.
Writen by Rukundo Olivier,A Dissertation Submitted in Partial Fulfillment of the Requirements for the award of Master of Engineering (June 2009).
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