Evolutionary design and adaptation of digital filters within an embedded fault tolerant hardware platform

Finite impulse response filters (FIRs) are crucial device for robust data communication and manipulation. Multiplierless filters have been shown to produce high performance systems with fast signal processing and reduced area. Furthermore, the distributed architecture inherent in multiplierless filters makes it a suitable candidate for fault tolerant design. Alternative approaches to the design of fault tolerant systems have been proposed using evolutionary algorithms (EAs) and the concept of evolvable hardware (EHW). This paper presents an evolvable hardware platform for the automated design and adaptation of multiplierless digital filters. Filters are realised within a dedicated programmable logic array (PLA). The platform employs a genetic algorithm to autonomously configure the PLA for a give set of coefficients. The ability of the platform to adapt to increasing numbers of faults was investigated through the "evolution" of a 31-tap low-pass FIR filter. Results show that the functionality of filters evolved on the PLA was maintained despite an increasing number of faults covering up to 25% of the PLA area. Additionally, three PLA initialisation methods were investigated to ascertain which produced the fastest fault recovery times. It was shown that seeding a population of random configuration-strings with the best configuration currently obtained resulted in a 6 fold increase in fault recovery speed over other methods investigated.