Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 25) Show all publications
Pettersson, P., Johannesson, P., Jacobson, B., Bruzelius, F., Fast, L. & Berglund, S. (2019). A statistical operating cycle description for prediction of road vehicles’ energy consumption. Transportation Research Part D: Transport and Environment, 73, 205-229
Open this publication in new window or tab >>A statistical operating cycle description for prediction of road vehicles’ energy consumption
Show others...
2019 (English)In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 73, p. 205-229Article in journal (Refereed) Published
Abstract [en]

We propose a novel statistical description of the physical properties of road transport operations by using stochastic models arranged in a hierarchical structure. The description includes speed signs, stops, speed bumps, curvature, topography, road roughness and ground type, with a road type introduced at the top of the hierarchy to group characteristics that are often connected. Methods are described how to generate data on a form (the operating cycle format) that can be used in dynamic simulations to estimate energy usage and CO2 emissions. To showcase the behaviour of the description, two examples are presented using a modular vehicle model for a heavy-duty truck: a sensitivity study on impacts from changes in the environment, and a comparison study on a real goods transport operation with respect to energy usage. It is found that the stop intensity and topography amplitude have the greatest impact in the sensitivity study (8.3% and 9.5% respectively), and the comparison study implies that the statistical description is capable of capturing properties of the road that are significant for vehicular energy usage. Moreover, it is discussed how the statistical description can be used in a vehicle design process, and how the mean CO2 emissions and its variation can be estimated for a vehicle specification.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
CO2 emissions, Commercial vehicles, Hierarchical Markov model, Operating cycle, Road description, Stochastic road model, Carbon dioxide, Energy utilization, Fleet operations, Markov processes, Roads and streets, Stochastic systems, Topography, Truck transportation, Markov model, Road models, Stochastic models
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39651 (URN)10.1016/j.trd.2019.07.006 (DOI)2-s2.0-85068800790 (Scopus ID)
Note

Funding details: Energimyndigheten; Funding details: Fellowships Fund Incorporated, FFI; Funding details: 44929-1; Funding text 1: The authors gratefully acknowledge financial support from the COVER project (44929-1), funded by the Swedish energy agency and the Swedish vehicle research and innovation programme (FFI).

Available from: 2019-08-07 Created: 2019-08-07 Last updated: 2019-08-16Bibliographically approved
Pettersson, P., Berglund, S., Jacobson, B., Fast, L., Johannesson, P. & Santandrea, F. (2018). A proposal for an operating cycle description format for road transport missions. European Transport Research Review, 10(2), Article ID 31.
Open this publication in new window or tab >>A proposal for an operating cycle description format for road transport missions
Show others...
2018 (English)In: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 10, no 2, article id 31Article in journal (Refereed) Published
Abstract [en]

Purpose: This article presents a proposal for an operating cycle format for describing transport missions of road vehicles, for example a logging truck fetching its cargo. The primary application is in dynamic simulation models for evaluation of energy consumption and other costs of transportation. When applied to product development, the objective is an ensemble of components and functions optimised for specific tasks and environments. When applied to selection of vehicle configuration, the objective is a vehicle specification tailored for its task. Method: The proposal is presented and its four main parts: road, weather, traffic and mission, are thoroughly explained. Furthermore, we implement the proposal in an example of a dynamic forward simulation model. Results: The example model is used for two case studies: a synthetic example of a complex transport mission (a logging truck fetching its cargo) that shows some advanced format features, and an example from a real vehicle log file (cargo transport) that seeks to compare the resulting simulated speed profile to the measured one. Conclusion: The results show that the proposed format works in practice. It can represent complex transport missions and it can be used to reproduce the main features of a logged speed profile even when combined with simple driver and vehicle models.

Keywords
Energy consumption simulation, Powertrain optimisation, Road format, Transport mission
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33987 (URN)10.1186/s12544-018-0298-4 (DOI)2-s2.0-85048855533 (Scopus ID)
Note

Funding details: Energimyndigheten; Funding details: FFI, Fellowships Fund Incorporated;  This work is a part of the OCEAN-project, funded by the Swedish Energy Agency via FFI.

Available from: 2018-07-03 Created: 2018-07-03 Last updated: 2018-08-17Bibliographically approved
Sandström, J., Johannesson, P. & Mikael, S. (2018). Reliability analysis with VMEA of a rack and pinion mechanism in a wave energy gravity accumulator. Göteborg
Open this publication in new window or tab >>Reliability analysis with VMEA of a rack and pinion mechanism in a wave energy gravity accumulator
2018 (English)Report (Other academic)
Abstract [en]

The method Variation and Mode Effect Analysis (VMEA) is successfully implemented for the AGMA based gear design of the rack pinion mechanism. The rack and pinion is a feature in Ocean Harvesting Technologies (OHT) gravity accumulator device. The purpose of it is to make the electrical power output to the grid more uniform. This is a novel technology where previous experience in designing is absent. The VMEA method is there for useful for incorporating all known uncertainties to estimate the uncertainty and reliability of the technology. This allows for adequate safety factors to be set so the desired reliability can be achieved.

The uncertainty and reliability analysis is performed for different OHT designs and methods where the reliability is calculated. This calculation can be used as basis for further analysis when more design details are determined and modifications are made, thus allowing for more optimized and reliable design to be made.

Place, publisher, year, edition, pages
Göteborg: , 2018. p. 38
Series
RISE Rapport ; 2018:07
Keywords
Reliablilty, VMEA, Gears, Marine Energy
National Category
Reliability and Maintenance Applied Mechanics Energy Engineering
Identifiers
urn:nbn:se:ri:diva-33068 (URN)978-91-88695-42-0 (ISBN)
Funder
Swedish Energy Agency, P40437-1
Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-08-17Bibliographically approved
Johannesson, P., Podgórski, K. & Rychlik, I. (2017). Laplace distribution models for road topography and roughness. International Journal of Vehicle Performance, 3(3), 224-258
Open this publication in new window or tab >>Laplace distribution models for road topography and roughness
2017 (English)In: International Journal of Vehicle Performance, ISSN 17453194, Vol. 3, no 3, p. 224-258Article in journal (Refereed) Published
Abstract [en]

Gaussian models are frequently used for road elevations. However, these models are often only valid for short sections of the road. Here we present a comprehensive approach to describe various aspects of road surface/elevation by using extensions of Gaussian models arising from random gamma distributed variances. These random variances result in the Laplace distribution and thus we refer to the so defined models as Laplace models. The approach is shown to perform well in modelling road topography, road roughness and multi-valued responses of forces and bending moments containing transients. The different Laplace models are presented together with numerical examples and Matlab code for simulation.

Keywords
road profile; topography; road roughness; generalised Laplacedistribution; non-Gaussian process; autoregressive process; PSD; power spectral density; ISO spectrum; IRI; international roughness index; fatigue damage.
National Category
Probability Theory and Statistics Vehicle Engineering Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:ri:diva-29420 (URN)10.1504/IJVP.2017.085032 (DOI)2-s2.0-85048889321 (Scopus ID)
Available from: 2017-05-02 Created: 2017-05-02 Last updated: 2019-05-29Bibliographically approved
Johannesson, P., Podgórski, K., Rychlik, I. & Shariati, N. (2016). AR(1) time series with autoregressive gamma variance for road topography modeling. Probabilistic Engineering Mechanics, 43, 106-116
Open this publication in new window or tab >>AR(1) time series with autoregressive gamma variance for road topography modeling
2016 (English)In: Probabilistic Engineering Mechanics, ISSN 0266-8920, E-ISSN 1878-4275, Vol. 43, p. 106-116Article in journal (Refereed) Published
Abstract [en]

A non-Gaussian time series with a generalized Laplace marginal distribution is used to model road topography. The model encompasses variability exhibited by a Gaussian AR(1) process with randomly varying variance that follows a particular autoregressive model that features the gamma distribution as its marginal. A simple estimation method to fit the correlation coefficient of each of two autoregressive components is proposed. The one for the Gaussian AR(1) component is obtained by fitting the frequency of zero crossing, while the autocorrelation coefficient for the gamma autoregressive process is fitted from the autocorrelation of the squared values of the model. The shape parameter of the gamma distribution is fitted using the explicitly given moments of a generalized Laplace distribution. Another general method of model fitting based on the correlation function of the signal is also presented and compared with the zero-crossing method. It is demonstrated that the model has the ability to accurately represent hilliness features of road topography providing a significant improvement over a purely Gaussian model.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Non-Gaussian time series, Gamma distributed variances, Generalized Laplace distribution, Road surface profile, Road roughness; Road hilliness
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-412 (URN)10.1016/j.probengmech.2015.12.006 (DOI)2-s2.0-84954350405 (Scopus ID)
Available from: 2016-06-23 Created: 2016-06-23 Last updated: 2019-06-11Bibliographically approved
Maghsood, R. & Johannesson, P. (2016). Detection of steering events based on vehicle logging data using hidden Markov models. International Journal of Vehicle Design, 70(3), 278-295
Open this publication in new window or tab >>Detection of steering events based on vehicle logging data using hidden Markov models
2016 (English)In: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 70, no 3, p. 278-295Article in journal (Refereed) Published
Abstract [en]

In vehicle design it is desirable to model the loads by describing load environment, customer usage and vehicle dynamics. In this study a method will be proposed for detection of steering events such as curves and manoeuvring using on-board logging signals available on trucks. The method is based on hidden Markov models (HMMs), which are probabilistic models that can be used to recognise patterns in time series data. In an HMM, 'hidden' refers to a Markov chain where the states are not observable. However, observations depending on the hidden Markov chain can be observed. The idea here is to consider the current driving event as the hidden state, while the on-board logging signals generate the observed sequence. Examples of curve detection are presented for both simulated and measured data on a truck. The classification results indicate that the method can recognise left and right turns with small misclassification errors.

Place, publisher, year, edition, pages
Inderscience Enterprises Ltd, 2016
Keywords
Baum-Welch algorithm, Event classification, Hidden Markov models, HMMs, Lateral acceleration, Markov chain, On-board logging signals, Steering events, Viterbi algorithm
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-396 (URN)10.1504/IJVD.2016.075780 (DOI)
Available from: 2016-06-22 Created: 2016-06-22 Last updated: 2019-06-13Bibliographically approved
Maghsood, R., Johannesson, P. & Wallin, J. (2016). Detection of steering events using hidden Markov models with multivariate observations. International Journal of Vehicle Systems Modelling and Testing, 11(4), 313-329
Open this publication in new window or tab >>Detection of steering events using hidden Markov models with multivariate observations
2016 (English)In: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 11, no 4, p. 313-329Article in journal (Refereed) Published
Abstract [en]

In this article we propose a method to identify steering events, such as curves and manoeuvres for vehicles. We use a hidden Markov model with multidimensional observations, to estimate the number of events. Three signals, lateral acceleration, steering angle speed and vehicle speed, are used as observations. We demonstrate that hidden Markov models with a combination of continuous and discrete distributions for observations can be used to detect steering events. Further, the expected number of events is estimated using the transition matrix of hidden states. The results from both measured and simulated data show that the method works well and accurately estimates the number of steering events.

Keywords
hidden Markov models, HMMs, Laplace distribution, discrete distribution, EM algorithm, steering events
National Category
Mathematics Natural Sciences Probability Theory and Statistics Engineering and Technology
Identifiers
urn:nbn:se:ri:diva-30019 (URN)10.1504/IJVSMT.2016.083752 (DOI)2-s2.0-85047075133 (Scopus ID)
Available from: 2017-06-29 Created: 2017-06-29 Last updated: 2019-06-13Bibliographically approved
Pettersson, P., Jacobsson, B., Johannesson, P., Berglund, S. & Laine, L. (2016). Influence of hill‐length on energy consumption for hybridized heavy transports in long‐haul transports. In: 7th Commercial Vehicle Workshop: . Paper presented at 7th Commercial Vehicle Workshop, May 12-13, 2016, Graz, Austria.
Open this publication in new window or tab >>Influence of hill‐length on energy consumption for hybridized heavy transports in long‐haul transports
Show others...
2016 (English)In: 7th Commercial Vehicle Workshop, 2016Conference paper, Published paper (Other academic)
Abstract [en]

Goods transports are big producers of CO2, i.e. consumers of energy. The conventional transport vehicles such as tractor-semitrailers can be replaced by long combination vehicles (LCVs). By doing so, fuel consumption will be reduced drastically, with up to 30%, mainly thanks to the reduced aerodynamic resistance per pay load mass and/or volume. Further reduction of CO2 improvements can be made by hybridization, if the road topography demands variable propulsion power due to up- and downhills. This gain is emphasized for heavier vehicles. So, hybridized LCVs are of special interest. When developing vehicles, or selecting vehicle for a certain transport, one needs to assume an operating cycle. To describe the operating cycle correctly is very important for this purpose. Traditionally, the magnitude of road grades is the only topography measure used to characterise the road. In this paper it is studied how an additional measure, hill length, influences these heavy hybridized LCVs. Together one can see these two measures as amplitude and wavelength. It is shown how energy saving varies for different types of roads (combinations of grade magnitude and hill-length) and different energy buffer sizes. Road topography is statistically generated for a good coverage of road types, but also examples of real roads are marked within these synthetic roads. The result can be combined with estimates of hybridization costs and conclusions can be drawn when it is beneficial to hybridize and with how large buffer. The main takeaways from the paper are that the potential energy savings for heavy LVCs due to hybridization are significant and that the hill-length is an important characteristic measure to include in operating cycle definitions.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-27923 (URN)
Conference
7th Commercial Vehicle Workshop, May 12-13, 2016, Graz, Austria
Available from: 2017-01-20 Created: 2017-01-20 Last updated: 2019-06-24Bibliographically approved
Johannesson, P., Podgórski, K. & Rychlik, I. (2016). Modelling roughness of road profiles on parallel tracks using roughness indicators. International Journal of Vehicle Design, 70(2), 183-210
Open this publication in new window or tab >>Modelling roughness of road profiles on parallel tracks using roughness indicators
2016 (English)In: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 70, no 2, p. 183-210Article in journal (Refereed) Published
Abstract [en]

The vertical road input is the most important load for durability assessments of vehicles. We focus on stochastic modelling of the parallel road profiles with the aim to find a simple but still accurate model for such bivariate records. A model is proposed that is locally Gaussian with randomly gamma distributed variances leading to a generalised Laplace distribution of the road profile. This Laplace model is paired with the ISO spectrum and is specified by only three parameters. Two of them can be estimated directly from a sequence of roughness indicators, such as IRI or ISO roughness coefficients. The third parameter, needed to define the cross-spectrum between the left and right road profiles, is estimated from the sample correlation. Explicit approximations for the expected fatigue damage for the proposed Laplace-ISO model are developed. The usefulness of the methods is validated using measured road profiles.

Place, publisher, year, edition, pages
Inderscience Enterprises Ltd., 2016
Keywords
Fatigue damage, Laplace distribution, Road irregularity, Road roughness, Vehicle durability
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-413 (URN)10.1504/IJVD.2016.074421 (DOI)
Available from: 2016-06-23 Created: 2016-06-23 Last updated: 2019-06-17Bibliographically approved
Jacobsson, L., Flansbjer, M., Johannesson, P., Lindqvist, J.-E., Brander, L. & Schouenborg, B. (2016). ONKALO POSE Experiment - Geological and Rock Mechanical Tests on Samples from a Heating Test at Olkiluoto.
Open this publication in new window or tab >>ONKALO POSE Experiment - Geological and Rock Mechanical Tests on Samples from a Heating Test at Olkiluoto
Show others...
2016 (English)Report (Other academic)
Series
POSIVA Working Report ; 2016:18
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-28342 (URN)
Available from: 2017-03-07 Created: 2017-03-07 Last updated: 2018-08-22Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6730-0214

Search in DiVA

Show all publications
v. 2.35.8