Mixed technology modelling and optimisation for automotive, energy harvesting and MEMS applications using VHDL-AMS

Abstract

This research work investigates methodologies for VHDL-AMS based mixed technology modelling and optimisation, specifically with automotive, energy harvesting and MEMS applications in mind. The contributions are summarised as follows: Firstly, methodologies that support modelling and simulation of mixed-domain automotive systems have been developed. VHDL-AMS and its standard packages have been used to generate efficient models of complex automotive systems.
Secondly, a novel, VHDL-AMS based optimisation of fuzzy logic controllers has been developed. The idea is to optimise the shapes of fuzzy logic membership functions using a genetic algorithm. Since the system to be optimised is also implemented in VHDLAMS, this methodology has resulted in an integrated performance optimisation system that is wholly implemented in a hardware description language.
Thirdly, the first complete VHDL-AMS modelling approach has been presented for the DATE’99 benchmark to model a portal crane and embedded control. The model was proposed for a DATE’99 technical panel discussion to compare different languages for system level specification. The obtained new benchmark results have proved the suitability of VHDL-AMS for creating executable specifications of heterogeneous embedded systems.
Fourthly, an automated energy harvester design flow which is based on a single HDL software platform that can be used to model, simulate, configure and optimise energy harvester systems has been proposed. VHDL-AMS has been used to incorporate various parts of the energy harvester (micro-generator, voltage booster, etc) into a single model. The salient feature of an integrated model is that it allows optimisation based on system performance, which is not possible in conventional modelling approaches.
Fifthly, to enhance the modelling capability of VHDL-AMS for systems with MEMS structures where distributed behaviour is essential, language extensions have been proposed to efficiently implement general partial differential equations. The extended language has been named VHDL-AMSP. A suitable preprocessor has been developed to automatically convert VHDL-AMSP into the existing VHDL-AMS 1076.1 standard, so that models with partial differential equations can be simulated using currently available simulators.
Finally, case studies have been presented to validate the developed methodologies. These case studies include: a portal crane and its embedded control, an automotive vibration isolation seating system, a fuzzy logic controller for automotive active suspension systems, a vibration-based electromagnetic energy harvester, and a MEMS accelerometer in high-order sigma-delta-modulator loops.

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