Key Technologies Of Digital Evolvable Hardware

Evolvable hardware is a kind of hardware system that integrates the evolutionary algorithm with the reconfigurable hardware organically. And the capabilities of self-organization, self-adaption and self-repair make it much larruping from the conventional hardware. There are great value of practicality and theoretical meaning to research on evolvable hardware, for the design of the new smart circuits and CMOS chips, for the construction of self-organizing, self-adaptive and self-repairing hardware systems, for the open problems of designing complex integrate circuits and CMOS chips, and for the requirement of high reliability and long mission life of the space aircrafts.In this thesis, key technologies of digital evolvable hardware, including the design and applications of evolutionary algorithm, the online evolution technologies of the complex digital circuits, and the system structure and fault-tolerance mechanisms of the evolvable hardware-based triple-module redundancy systems, have been explored.1. The model and design steps of evolutionary algorithm is given, and analysis and comparison is given on its four main branches. A system structure and design method of adaptive mathematical morphology filter based on evolutionary algorithm is proposed. Not only filtering algorithms can be adjusted adaptively, but also shape, amplitude and width of the structure elements can be regulated automatically. Taking genetic algorithm as optimizing engine, the architecture of filter is implemented on Xilinx XCV2000-E FPGA and optimized online. Results of online filtering show that the filter can adjust its architecture and parameters adaptively according to different types of noises, thus has good robustness and better filtering performance than mean filter and median filter. Moreover, the filter is implemented on hardware, which makes it a very promising filter for embedded systems.2. An immune genetic algorithm based on the monkey-king's marriage mechanism (MMIGA) is proposed to accelerate the convergence speed. The antibody set is modeled as a monkey colony, which is divided into male and female sub-colonies according to the individual's affinity to the antigen, and the super individual is the monkey-king. All the female monkeys marry to the monkey-king with a certain probability and then perform gene mutation to breed descendants; the male monkeys breed descendants by simulating the immune response process of cloning, adaptive mutating, annealing keeping and fuzzy dislike matrix selecting; whereas the monkey-king is maintained to the next generation. The principles, steps and convergence proof of MMIGA are given. Contrast studies in function optimization, online evolutionary design of digital circuits and image filter indicate the superior performance of MMIGA over the genetic algorithm.3. The difficulties and probable solutions on evolving complerx digital circuits are analyzed, and aiming at the difficulty of evolving complex circuits, a growing evolutionary approach suitable for online evolution is proposed. The complex digital circuit is decomposed into simpler seed circuits, then the evolution approach that simulates the process of the plant's growth unties the circuits'scalability. Meanwhile, in order to solve the online evaluation problem, an incremental evaluation approach is used to substitute for the conventional exhaustive evaluation method, which enhanced the evolution speed greatly. Contrast results show that the growing approach performs more effective than evolving directly, whether on the electric circuits'scale or the evolution speed.4. Aiming at evolving systems-on-chip, a new online design method is proposed, in which the run-time parameterizable (RTP) cores are utilized as building blocks, and the function of the soft IP core may change real time according to consumer's demand. The concept and model of evolvable RTP core is given, and the design method is proof-tested by a HDB3 coder system-on-chip. Using the building blocks of evolvable RTP cores, digital hardware systems can be evolutionary designed online, and perform self-adapting and self-repairing online, thus open a viable way for the real-world applications of evolvable hardware.5. A new system structure and design method of triple-module redundancy (TMR) systems with multi-ply online self-repair mechanisms that need not affect the system's normal operation is proposed by introducing evolvable hardware into the traditional TMR system. The system has a structure of TMR in the mass, which can check the fault module autonomously; each module is made up of subassemblies with spare parts, and can recover from fault quickly by switching to the spare parts; while each subassembly in the module can be repaired through evolution; moreover, redundant circuits with different structures are applied to avoid the synchronously arriving of fault at more than 2 modules. The system structure and reliability model is given, the reliability formula is educed, and the reliability of the system is analyzed in theory. The design method is proof-tested by a TMR HDB3 coder system-on-chip. It is shown that the reliability of the system has been enhanced greatly.