Path design and receding horizon control for collision avoidance system of cars

The paper deals with path design and control realization problems of collision avoidance systems (CAS) of cars (ground vehicles). CAS emergency path design is based on the principle of elastic band with improved reaction forces for road borders and static obstacles allowing quick computation of the force equilibrium. The CAS path (reference signal) is smoothed and realized using receding horizon control (RHC). The car can be modelled by full (non-affine) or simplified (input affine) nonlinear models. The nonlinear predictive control problem is solved by using time varying linearization along appropriately chosen nominal control and state sequences, and analytical solution of the minimization of a quadratic criterion satisfying end-constraint. Differential geometric approach (DGA), known from control literature for the input affine nonlinear model, has been used for control initialization in the first horizon. For state estimation Kalman filters and measurements of two antenna GPS and Inertial Navigation System (INS) are used. A stand-alone software has been been developed using the C Compiler of MATLAB R2006a satisfying real time expectations

Resonant whirling of two-piece propshafts in rear-wheel-drive cars

Many modern cars with rear-wheel drives have a two-piece, rather than the traditional one-piece, props haft (or tail-shaft). The two-piece shaft requires less floor clearance, and hence a smaller floor tunnel, and does not suffer from the high-speed twisting resonances to which the one-piece shaft is susceptible. The two-piece shaft is, however, susceptible to a lower speed, high load (high torque) phenomenon in which the propshaft whirls with increasing amplitude until its restraining rubber bush is fully compressed in its mounting bracket, causing a thump sound. The whirling amplitude builds up periodically, so that a regular series of thumps is heard at a frequency of about 5 per second. The effect is very sensitive to the properties of the rubber bush and to its temperature. Different designs of bush are used by different makers, each with the purpose of minimizing both the whirling problem and the transmission of other vibrations to the car body. GMH has a particular design which it would prefer not to vary, because of retooling costs. It can however vary the properties of the rubber material itself. By trial and error it has achieved rubber properties which control the whirling problem to an acceptable level under normal conditions. GMH posed the question, to the MISG, of whether one can give theoretical guidelines for optimal rubber properties. This might lead to improved control of the whirling problem. It would also be useful for new and modified propshafts, if it could replace the tedious trial and error process previously employed. GMH were also anxious to gain a better understanding of the whirling phenomenon, and felt, with us, that a mathematical description of the phenomenon was a prerequisite for the study of the rubber properties. The thumping phenomenon is observed at both 40 and 80 kph approximately, although the phenomenon had a different quality at these two speeds

Bayesian quantification for coherent anti-Stokes Raman scattering spectroscopy

We propose a Bayesian statistical model for analyzing coherent anti-Stokes Raman scattering (CARS) spectra. Our quantitative analysis includes statistical estimation of constituent line-shape parameters, underlying Raman signal, error-corrected CARS spectrum, and the measured CARS spectrum. As such, this work enables extensive uncertainty quantification in the context of CARS spectroscopy. Furthermore, we present an unsupervised method for improving spectral resolution of Raman-like spectra requiring little to no \textit{a priori} information. Finally, the recently-proposed wavelet prism method for correcting the experimental artefacts in CARS is enhanced by using interpolation techniques for wavelets. The method is validated using CARS spectra of adenosine mono-, di-, and triphosphate in water, as well as, equimolar aqueous solutions of D-fructose, D-glucose, and their disaccharide combination sucrose

Modeling the hall-petch effect with a gradient crystal plasticity theory including a grain boundary yield criterion

Abstract. A strain gradient crystal plasticity theory including the gradient of the equiv- alent plastic strain ∇γeq is discussed. A grain boundary yield condition is proposed in order to account for the influence of the grain boundaries. Periodic tensile test simulations show the mechanical predictions of the numerical model

An Investigation Into the Effects of Various Transport Policies on the Levels of Motorised Traffic in Great Britain in 2006

This Working Paper presents the results of tests of various transport policies which could potentially have a major impact on private car travel and hence gain environmental benefits at a national level. The forecasting methodology was to take OPCS population forecasts for year 2006 in 28 age/sex/area type categories, predict the car available percentage of person in each category in 2006, and then predict trip mileage growth (by three mode types for the 28 categories each subdivided into car available and car non-availahle. For the latter two predications, NTS data for 1985/6 and 1991/3 were compared and projected forward with various adjustments. The effect of individual transport policies on trip rates for individual cells was determined from results derived from other studies, coupled with a consideration of economic theory. Of the tests considered, only the tripling of fuel prices for private mode transport was ahle to hold private mode mileage in 2006 at ahout its 1992 level