Kening Zhang, Ronald F. DeMara, Carthik A. Sharma, "Consensus-based Evaluation 
for Fault Isolation  and On-line Evolutionary Regeneration," submitted to the 
International Conference in Evolvable Systems, Barcelona, Spain, September 12 - 
14, 2005.

Abstract :
While the fault repair capability of Evolvable Hardware (EH) approaches have 
been previously demonstrated,  further improvements to fault handling capability 
can be achieved by exploiting population diversity during all phases of the 
fault  handling process. A new paradigm for online EH regeneration using Genetic 
Algorithms (GAs) called Consensus Based Evaluation (CBE) is developed where the 
performance of individuals is assessed based on broad consensus of the 
population instead of a conventional fitness function. Adoption of CBE enables 
information contained in the population to not only enrich the evolutionary 
process, but also support fault detection and isolation. On-line regeneration of 
functionality is achieved without additional test vectors by using the results 
of competitions between individuals in the population. Relative fitness measures 
support adaptation of the fitness evaluation procedure to support graceful 
degredation even in the presence of unpredictable changes in the operational 
environment, inputs, or the FPGA application. Application of CBE to FPGA-based 
multipliers demonstrates 100%  isolation of randomly injected stuck-at faults 
and evolution of a complete regeneration within 135 repair iterations while 
precluding the propagation of any discrepant output. The throughput of the 
system is maintained at 85.35% throughout the repair process.