Bundle adjustment using single-track vehicle model

This paper describes a method for estimating the 6-DoF viewing parameters of a calibrated vehicle-mounted camera. Visual features are combined with standard in-vehicle sensors and a single-track vehicle motion model in a bundle adjustment framework to produce a jointly optimal viewing parameter estimate. Results show that the vehicle motion model in combination with in-vehicle sensors exhibit good accuracy in estimating planar vehicle motion. This property is preserved, when combining these information sources with vision. Furthermore, the accuracy obtained from vision-only in direction estimation is not only maintained, but in fact further improved, primarily in situations where the matched visual features are few

A methodology and a tool for evaluating hybrid electric powertrain configurations

This paper describes a methodology for automatic optimisation of hybrid electric powertrains. This methodology is developed and implemented in a tool, CAPSimO, and the paper is written in the form of describing the tool. Given the user inputs, which are dynamic vehicle model, driving cycle and optimisation criterion, the tool first produces a simplified powertrain model in a form of static maps, before dynamic programming is used to find an optimal power split which minimises the chosen criterion. The tool does not require that the vehicle model is transparent, which makes it possible to work on models hidden for intellectual property reasons. The paper presents two examples of powertrain evaluation, in terms of fuel consumption, for a parallel and a parallel-series powertrain

Vehicle Independent Road Resistance Estimation Using Connected Vehicle Data

This paper is investigating if it possible to use vehicle log data to estimate vehicle independent road resistance parameters that can have large local variations and change rapidly, such as wind speed, wind direction and road surface conditions. The estimated parameters can be used to improve range estimation, route planning and vehicle energy management. The advantage with using vehicle independent parameters is that data from any vehicle can be used to improve the estimation and that all vehicles can benefit from the estimated data. An analytical solution previously presented for parameter estimation is verified on vehicle log data. Results show that the method works reasonably well for wind speed estimation and that changes in road conditions can be detected. Side wind affects need to be considered in future wor

Air-management and fueling strategy for diesel engines from multi-layer control perspective

This paper proposes a novel control design procedure for air management and fueling strategy (AMFS) of diesel engines in lights of a multi-layer control structure (MLCS). Furthermore, novel sufficient stability conditions in the form of linear matrix inequalities are derived (using slack variables to reduce the conservativeness) for grid-based linear parameter-varying systems. The gain-scheduled controller for AMFS is designed to track a reference torquetrajectory requested by higher control layers from MLCS, with the objective of minimizing diesel consumption and pollutants\u27 emissions. For controller design a reduced order grid-based linear parameter-varying model is obtained from the detailed benchmark model published by Eriksson et al. (2016). The controller is validated on the benchmark model using the road profile S\uf6der\ue4lje-Norrk\uf6ping

Development of simplified air drag models including crosswinds for commercial heavy vehicle combinations

Accurate range prediction requires good knowledge of the prevailing wind conditions and how they affect the energy consumption of the ego vehicle. A few different simplified vehicle air drag models that explicitly include the effect from crosswinds are presented and compared through some objective criteria. The models are developed from the normal air drag equation where the effect from wind is implicit and therefore often forgotten or neglected. The purpose is to find a low-complexity model complementing CFD models and wind tunnel tests, that can be used for range estimation and predictive energy management algorithms. To simplify online estimation, a requirement is that the air drag models only contain a few tuning parameters. The models are validated against CFD calculations for a few vehicle combinations and the best models show good accuracy for air attack angles up to at least 60 degrees. It is shown that the parameters of the simplified models can loosely be connected to some basic geometrical attributes of a vehicle combination so it should be possible to give at least a rough estimate of the parameters of a simplified model based on these geometrical attributes. This is useful for making a first estimate of the aerodynamic properties of a vehicle combination after major changes in the exterior, e.g. when adding a trailer. It also highlights that the size and the shape of the vehicle side may be mainly responsible for the high longitudinal air drag sensitivity to crosswinds for large vehicle combinations

Quadratic approximation based heuristic for optimization-based coordination of automated vehicles in confined areas

We investigate the problem of coordinating multiple automated vehicles (AVs) in confined areas. This problem can be formulated as an optimal control problem (OCP) where the motion of the AVs is optimized such that collisions are avoided in cross-intersections, merge crossings, and narrow roads. The problem is combinatorial and solving it to optimality is prohibitively difficult for all but trivial instances. For this reason, we propose a heuristic method to obtain approximate solutions. The heuristic comprises two stages: In the first stage, a Mixed Integer Quadratic Program (MIQP), similar in construction to the Quadratic Programming (QP) sub-problems in Sequential Quadratic Programming (SQP), is solved for the combinatorial part of the solution. In the second stage, the combinatorial part of the solution is held fixed, and the optimal state and control trajectories for the vehicles are obtained by solving a Nonlinear Program (NLP). The performance of the algorithm is demonstrated by a simulation of a non-trivial problem instance.Comment: To be published in the 61st IEEE Conference on Decision and Control (CDC 2022). arXiv admin note: substantial text overlap with arXiv:2210.1473

Moisture content prediction of rain-exposed wood: Test and evaluation of a simple numerical model for durability applications

Abstract in FrenchDecay-prediction models can be used to predict the service life of wooden components. However, knowledge of how the material climate, i.e. moisture content and material temperature, varies with time is required. A reliable material climate prediction model is therefore crucial in situations when measurements are not viable. The aim of this paper is to develop and assess the performance of a simple numerical moisture transport model for rain-exposed wood. The main focus is on the influence of rain and moisture transport in the transversal direction.First, a model based on Fick’s second law of diffusion was calibrated against laboratory measurements where wooden boards were exposed to artificial rain. Second, the model was tested against field-test measurements on wooden boards in use-class 3.1, i.e. above-ground, exposed to rain and free to dry. The influence of rain was investigated by studying the difference between sheltered and exposed specimens over time. Finally, the model was applied to a number of Swedish climates and two different decay-prediction models were used to assess the output.The main conclusion is that the influence of rain can be reproduced with sufficient accuracy for the particular application. The error between the numerical result and measurements tends to increase with decreasing temperature and at high moisture contents. However, the total error is reduced when the moisture content history is post-processed in a decay-prediction model as the rate of decay decreases with decreasing temperature

Rökning i hyreslägenheten och på tillhörande balkong

Rökning ses enligt praxis idag ännu som något normalt och något hyresgästen får göra i lägenheten och på tillhörande balkong. Rökning i hyreslägenheten kan dock medföra att tvister uppstår mellan hyresgäst och hyresvärd av olika skäl. Det står klart att en hyresgäst kan bli skadeståndsskyldig för skador som orsakats av rökning i lägenheten. De kriterier som bedöms när det gäller frågan om hyresgästens skadeståndsskyldighet är dels vilka skador som uppstått och hur grava dessa är, under hur lång tid skadorna uppstått samt hur hyresgästen agerat för att förebygga att skador uppstår. Förebyggande åtgärder kan bland annat vara att vädra ut lukten och städa. I bedömningen torde även vikt läggas vid hyresvärdens underhållsansvar. Även frågan om det föreligger rökförbud i lägenheten är av betydelse för bedömningen. Kvarvarande missfärgningar och röklukt från tidigare hyresgäst kan anses vara en brist som hyresvärden måste åtgärda. Utifrån inträngande röklukt i en bostadslägenhet kan även anses som en brist i hyreslagens mening om denna tränger in p.g.a. brister i fastighetens konstruktion. Störningen får dock inte vara helt tillfällig. Avseende rök som tränger in på balkong eller genom öppna fönster och dörrar konstateras att hyresgäster har rätt att röka på sin balkong om inte den störde hyresgästen kan visa att rökning har förekommit i så stor utsträckning att det inte skäligen skulle tålas. Var gränsen går för detta har inte kunnat fastställas. När det gäller rökförbud som hyresvillkor kan sådana i vart fall anses gällande om dessa införts i avtalet när detta slöts. För att kunna anses skäligt skall villkoret ha påkallats av ett särskilt intresse, gälla samtliga hyresgäster och rent objektivt ligga i hyresvärdens intresse att upprätthålla. Om en hyresgäst bryter mot sådant gällande hyresvillkor kan denne inte endast p.g.a. detta åläggas skadeståndsskyldighet eller att hyresavtalet förverkas eller inte förlängs. Villkoret kan dock spela en roll i bedömningen av hyresgästens ansvar. Det går idag inte att säga att rättsutvecklingen går mot ett förbjudande av rökning i flerfamiljshus men med bostadsbolagens tillhandahållande samt hyresgästernas efterfrågan på rökfria lägenheter kan en förändring av lagstiftningen komma att ske på längre sikt.According to Swedish law, smoking is considered normal behavior and tenants are allowed to smoke in a rented flat. Smoking in the rented flat may still result in disputes between tenants and landlords, for various reasons. It has been established that a tenant can be liable for damage caused by smoking in the flat. The criteria considered for the tenant's liability is the damage caused and its severity, the time during which the damage occurred, and how the tenant acted to prevent the damage. The landlord's responsibilities for maintenance and whether there is a smoke ban in the flat are also considered. Preventive measures can include cleaning and airing. Residual discoloration and smoke odour from previous tenant can be considered damage, against which the landlord must take measures. The smell of smoke coming from another flat can also be considered a defect if it is caused by defects in the building's construction. Regarding smoke entering by the balcony or through open windows and doors, it has been concluded that tenants have the right to smoke on their balcony. This is if the affected tenant cannot prove that smoking has occurred to such an extent that it cannot reasonably be tolerated. The boundaries for the extent of smoking that cannot reasonably be tolerated has not been established by law or court practice. In the case of smoking bans as a term of rental contracts, the term could at least be considered valid if implemented in the agreement when it was signed. To be considered fair, the term has to be initiated by a special interest, apply to all tenants and objectively be in the interest of the landlord to maintain. If a tenant violates a current rental term, the tenant may not be liable for damages or to forfeit the lease due only to the breach of that term. The rental term may play a role in the assessment of the tenant's responsibility. It is currently not possible to say that there is trend in legal development towards banning smoking in rental housing, but with the provision and the tenants' demand for non-smoking apartments, a change in the law may occur in a longer perspective

Student and supervisor understanding of generic criteria for specific projects – A pilot study in an engineering education context

This paper offers an account of a pilot investigation into students’ and supervisors’ understanding and interpretation of university-wide guidelines and criteria for theses in engineering education. The university-wide criteria present both a means and a challenge for enhancing theses quality. To the extent that the means lies in indicating the expected standard, the challenge lies in the difficulty to interpret criteria relative specific student projects in order to decide what the criteria imply for specific engineering disciplines and projects. Consequently, there is a risk that despite articulating guidelines and criteria, the quality of theses does not improve since the discipline’s standards are insufficiently articulated by supervisors and poorly internalised by students. We suggest that revised supervision processes promoting student ownership and their informed engagement in criterion-based self- and peer-assessment might offer ways of promoting disciplinary discursive expertise for internalising standards by addressing the difficulty of understanding assessment criteria