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This work involves a study on laser ignition (LI) in an internal combustion (IC) engine and investigates the effects on control of engine combustion performance and stability of varying specific laser parameters (beam energy, beam quality, minimum beam waist size, focal point volume and focal length). A Q-switched Nd?:?YAG laser operating at the fundamental wavelength 1064?nm was successfully used to ignite homogeneous stoichiometric gasoline and air mixtures in one cylinder of a 1.6?litre IC test engine, where the remaining three cylinders used conventional electrical spark ignition (SI). A direct comparison between LI and conventional SI is presented in terms of changes in coefficient of variability in indicated mean effective pressure (COVIMEP) and the variance in the peak cylinder pressure position (VarPPP). The laser was individually operated in three different modes by changing the diameter of the cavity aperture, where the results show that for specific parameters, LI performed better than SI in terms of combustion performance and stability. Minimum ignition energies for misfire free combustion ranging from 4 to 28?mJ were obtained for various optical and laser configurations and were compared with the equivalent minimum optical breakdown energies in air.

This paper presents a nonparametric approach to the design of feedback for stable invertible MIMO plants using Frobenius norm H∞, Hadamard weighted feedback control for mixed-sensitivity criterea. It is shown that the corresponding mixed sensitivity performance function may be reduced to one of quasi-circular type, appropriate for using Nehari-solution algorithms to achieve good solution-convergence by disk iteration. A non-parametric interpolation scheme is developed to retain the quasi-circular function and to guarantee internal stability. The disk-iteration method of Helton-Merino for analytic function optimisation may then be applied to optimise the mixed sensitivity criterion subject to the required internal stability constraints. The complete design process is thus based entirely on the plant frequency response. A simulation study of a 2 × 2 MIMO automotive IC engine torque and fuelling controller is given which compares the Frobenius norm H∞ method with a maximum singular norm H∞ controller . It is shown that the Frobenius norm method gives direct control over disturbance decoupling but otherwise enjoys similar robustness and performance to the maximum singular norm controller. The approach thus presents a nonparametric alternative to the state-space Frobenius norm methods of Van Diggelen and Glover.

This paper describes a neural-network (NN)-based scheme for the control of a cylinder peak pressure position (PPP)—also known as the location of peak pressure (LPP)—by spark timing in a gasoline internal combustion engine. The scheme uses the ionization current to act as a virtual sensor, which is subsequently used for PPP control. A NN is trained offline on principal-component analysis data to predict the cylinder peak pressure position under dynamically varying engine load, speed, and spark advance (SA) settings. Experimental results demonstrate that the PPP prediction by the NN correlates well with those measured from in-cylinder pressure sensors across transients of load, SA, and engine speeds. The dynamic training data allow rapid model identification across the identified engine range, as opposed to just fixed operating points. A linear robust constrained-variance controller, which is a robustified form of the minimum variance controller, is used to regulate the PPP by SA control action, using the NN as a PPP sensor. The control scheme is validated by experimental implementation on a port fuel-injected four-cylinder 1.6 l gasoline internal combustion engine.

Various types of optical fibres have been investigated and compared for delivering high power laser beams to an optical plug (comprising of lenses and an optical window) for the application of laser-induced ignition of gasoline and air mixtures in an automotive internal combustion engine. Three main types of optical fibre were examined: multi-mode step index silica, sapphire and photonic crystal. The fibres had various core sizes ranging from 35 to 600 μ ma nd numerical apertures between 0.046 and 0.64. A Q-switched Nd:YAG laser operating at the fundamental wavelength 1064 nm with a pulse length of 15 ns was used for the testing. Fibre output beam properties, including beam mode quality, output divergence, transmission losses, beam energy thresholds and effects of engine vibration were investigated. These fibre beam properties were compared with known beam parameters for laser ignition to assess the suitability of such fibres for a laser ignition system. Online fibre delivery laser ignition engine tests were performed with the most suitable fibres, which showed that combustion could be achieved with this system despite a relatively large percentage of misfires.