Implementation of Block-based Neural Networks on Reconfigurable Computing Platforms

Block-based Neural Networks (BbNNs) provide a flexible and modular architecture to support adaptive applications in dynamic environments. Reconfigurable computing (RC) platforms provide computational efficiency combined with flexibility. Hence, RC provides an ideal match to evolvable BbNN applications. BbNNs are very convenient to build once a library of neural network blocks is built. This library-based approach for the design of BbNNs is extremely useful to automate implementations of BbNNs and evaluate their performance on RC platforms. This is important because, for a given application there may be hundreds to thousands of candidate BbNN implementations possible and evaluating each of them for accuracy and performance, using software simulations will take a very long time, which would not be acceptable for adaptive environments. This thesis focuses on the development and characterization of a library of parameterized VHDL models of neural network blocks, which may be used to build any BbNN. The use of these models is demonstrated in the XOR pattern classification problem and mobile robot navigation problem. For a given application, one may be interested in fabricating an ASIC, once the weights and architecture of the BbNN is decided. Pointers to ASIC implementation of BbNNs with initial results are also included in this thesis

Analog VLSI circuits as physical structures for perception in early visual tasks

none4A variety of computational tasks in early vision can be formulated through lattice networks. The cooperative action of these networks depends on the topology of interconnections, both feedforward and recurrent ones. This paper shows that it is possible to consider a distinct general architectural solution for all recurrent computations of any given order. The Gaborlike impulse response of a second-order network is analyzed in detail, pointing out how a near-optimal filtering behavior in space and frequency domains can be achieved through excitatory/inhibitory interactions without impairing the stability of the system. These architectures can be mapped, very efficiently at transistor level, on very large scale integration (VLSI) structures operating as analog perceptual engines. The problem of hardware implementation of early vision tasks can, indeed, be tackled by combining these perceptual agents through suitable weighted sums. A 17-node analog current-mode VLSI circuit has been implemented on a CMOS 3mhum, NWELL, single-poly, and doublemetal technology, to demonstrate the feasibility of the approach. Applications of the perceptual engine to various machine vision algorithms are proposedRAFFO L.; SABATINI S.P.; BO G.M.; G. M.BISIORaffo, L.; Sabatini, SILVIO PAOLO; Bo, G. M.; Bisio, Giacom