Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 43) Show all publications
Andersson, K., Hagnestål, A. & Sellgren, U. (2018). A flexible chain proposal for winch based point absorbers. In: Proceedings of the ASME 2018 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2018: August 26-29, 2018, Quebec City, Quebec, Canada. Paper presented at ASME 2018 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference.
Open this publication in new window or tab >>A flexible chain proposal for winch based point absorbers
2018 (English)In: Proceedings of the ASME 2018 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2018: August 26-29, 2018, Quebec City, Quebec, Canada, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Ocean wave power is a promising renewable energy source for future energy production. It has however been difficult to find a cost-effective solution to convert the wave energy into electricity. The harsh marine environment and the fact that wave power is delivered with high forces at low speeds makes design of durable mechanical structures and efficient energy conversion challenging. The dimensioning forces strongly depend on the wave power concept, the Wave Energy Converter (WEC) implementation and the actual Power TakeOff (PTO) system. A WEC using a winch as a Power Take-Off system, i.e. a Winch Based Point Absorber (WBPA), could potentially accomplish a low Levelized Cost Of Energy (LCOE) if akey component - a low-cost, durable and efficient winch that can deal with high loads - can be developed. A key problem for achieving a durable winch is to find a force transmitting solution that can deal with these high loads and handle up to 80 million cycles. In this article we propose a design solution for a force transmitting chain in a WBPA system where elastomeric bearings are used as a means to achieve the relative motion between the links in the chain. With this solution no sliding is present and the angular motion is achieved as a deformation in the elastomeric bearing when the chain is winded on a drum. The link was designed primarily to minimize the number of joints in the chain: Thereby the maximum allowed relative angle between the links when rolled up over the drum should be as large as possible within practical limits. The angle is to be handled by the elastomeric bearing. A detailed strength analysis of the link has been performed as well as topology optimization to increase the strength to weight ratio. A test rig for a first proof of concept testing has been developed and the first preliminary test results indicate that this concept with using elastomeric bearings can be a potential solution for a durable chain and should be analyzed further for fatigue conditions and under water operations. 

Keywords
Chain transmission; Elastomeric bearing; Power take-off system; Wave power
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-240567 (URN)000461131000020 ()2-s2.0-85056899645 (Scopus ID)
Conference
ASME 2018 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference
Note

QC 20190107

Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2019-04-26Bibliographically approved
Andersson, K., Hagnestål, A. & Sellgren, U. (2018). Design of a flexible chain for winch based point absorbers. In: Proceedings of NordDesign: Design in the Era of Digitalization, NordDesign 2018: . Paper presented at 13th Biennial NordDesign 2018.
Open this publication in new window or tab >>Design of a flexible chain for winch based point absorbers
2018 (English)In: Proceedings of NordDesign: Design in the Era of Digitalization, NordDesign 2018, 2018Conference paper, Published paper (Refereed)
National Category
Ocean and River Engineering
Identifiers
urn:nbn:se:kth:diva-240563 (URN)2-s2.0-85057143261 (Scopus ID)
Conference
13th Biennial NordDesign 2018
Note

QC 20190107

Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2019-04-09Bibliographically approved
Hagnestål, A., Sellgren, U. & Andersson, K. (2017). Durable winch-based point absorbers. In: Proceedings of the 12th European Wave and Tidal Energy Conference 27th Aug - 1st Sept 2017, Cork, Ireland: . Paper presented at Ewtec 2017: The 12th European Wave and Tidal Energy Conference 27th Aug - 1st Sept 2017, Cork, Ireland. European Wave and Tidal Energy Conference
Open this publication in new window or tab >>Durable winch-based point absorbers
2017 (English)In: Proceedings of the 12th European Wave and Tidal Energy Conference 27th Aug - 1st Sept 2017, Cork, Ireland, European Wave and Tidal Energy Conference , 2017Conference paper, Published paper (Refereed)
Abstract [en]

Wave power could give a significant contribution to a

future sustainable energy system if the Levelized Cost Of Energy

can be reduced to a competitive level. Winch-based point

absorbers could potentially accomplish this if a key component –

a low-cost, durable and efficient winch that can deal with high

loads – can be developed. In this article the possibilities of winchbased

point absorbers and the challenges that need to be

overcome are described. Further, the possibilities to design such

winches are explored and several different design approaches are

evaluated and compared. At present, we believe that such a

winch solution can be found although more research is needed to

develop a full concept, and the most promising solutions so far

involve inverted tooth chains, flat UHMwPE fiber (Dyneema)

bands and flat carbon fibre structures.

Place, publisher, year, edition, pages
European Wave and Tidal Energy Conference, 2017
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-219531 (URN)
Conference
Ewtec 2017: The 12th European Wave and Tidal Energy Conference 27th Aug - 1st Sept 2017, Cork, Ireland
Note

QC 20180112

Available from: 2017-12-07 Created: 2017-12-07 Last updated: 2018-01-12Bibliographically approved
Ismoilov, A., Sellgren, U., Andersson, K. & Löfgren, B. (2015). A comparison of novel chassis suspended machines for sustainable forestry. Journal of terramechanics, 58, 59-68
Open this publication in new window or tab >>A comparison of novel chassis suspended machines for sustainable forestry
2015 (English)In: Journal of terramechanics, ISSN 0022-4898, E-ISSN 1879-1204, Vol. 58, p. 59-68Article in journal (Refereed) Published
Abstract [en]

Cut-to-length logging (CTL) is a mechanized harvesting process where trees are delimbed and cut to length directly at the stump. The main challenges for the manufacturers of forestry machines for CTL logging are to address new customer demands and tougher health and environmental legislations by finding means that: (1) further increase the harvesting and log transportation productivity, e.g. by enabling operation on eco-soils, (2) reduce the damage to the soil, e.g. by controlling the ruts depth and preserving the root layer, (3) reduce exhaust emissions, e.g. by reducing the rolling resistance, and (4) reducing the daily vibration dosage for the machine operators, e.g. by active chassis and cabin damping. This paper presents of a number of passive forwarder chassis suspension concepts and compares their performance from three perspectives: their gentleness to terrain and operator, as well as their potential for improved fuel efficiency. Based on multi-body dynamics simulations, it is shown that a passive pendulum arm suspension can reduce the lateral accelerations in a passively suspended cabin with 50% compared to traditional bogie machines when travelling in rough hard terrain.

Keywords
Bogie, Forest machine, Ground damage, Mobility, Multibody dynamics simulation, Off-road, Rough terrain
National Category
Environmental Management
Identifiers
urn:nbn:se:kth:diva-165204 (URN)10.1016/j.jterra.2015.01.002 (DOI)000351800200006 ()2-s2.0-84923862318 (Scopus ID)
Note

QC 20150507

Available from: 2015-05-07 Created: 2015-04-24 Last updated: 2017-12-04Bibliographically approved
Ahmad, A., Andersson, K. & Sellgren, U. (2015). An Optimization Approach Toward a Robust Design of Six Degrees of Freedom Haptic Devices. Journal of mechanical design (1990), 137(4), Article ID 042301.
Open this publication in new window or tab >>An Optimization Approach Toward a Robust Design of Six Degrees of Freedom Haptic Devices
2015 (English)In: Journal of mechanical design (1990), ISSN 1050-0472, E-ISSN 1528-9001, Vol. 137, no 4, article id 042301Article in journal (Refereed) Published
Abstract [en]

This work presents an optimization approach for the robust design of six degrees of freedom (DOF) haptic devices. Our objective is to find the optimal values for a set of design parameters that maximize the kinematic, dynamic, and kinetostatic performances of a 6-DOF haptic device while minimizing its sensitivity to variations in manufacturing tolerances. Because performance indices differ in magnitude, the formulation of an objective function for multicriteria performance requirements is complex. A new approach based on Monte Carlo simulation (MCS) was used to find the extreme values (minimum and maximum) of the performance indices to enable normalization of these indices. The optimization approach presented here is formulated as a methodology in which a hybrid design-optimization approach, combining genetic algorithm (GA) and MCS, is first used. This new approach can find the numerical values of the design parameters that are both optimal and robust (i.e., less sensitive to variation and thus to uncertainties in the design parameters). In the following step, with design optimization, a set of optimum tolerances is determined that minimizes manufacturing cost and also satisfies the allowed variations in the performance indices. The presented approach can thus enable the designer to evaluate trade-offs between allowed performance variations and tolerances cost.

Keywords
Tau Parallel Robot, Inverse Dynamics, Stewart Platform, Sensitivity-Analysis, Manipulators, Workspace
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-166333 (URN)10.1115/1.4029514 (DOI)000352573500009 ()2-s2.0-84993661824 (Scopus ID)
Note

QC 20150508

Available from: 2015-05-08 Created: 2015-05-07 Last updated: 2017-12-04Bibliographically approved
Andersson, K. (2015). Evaluation of a model based learning approach for engineering design. In: INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE, 2015, VOL 3: . Paper presented at ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Boston, MA, AUG 02-05, 2015. , Article ID UNSP V003T04A013.
Open this publication in new window or tab >>Evaluation of a model based learning approach for engineering design
2015 (English)In: INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE, 2015, VOL 3, 2015, article id UNSP V003T04A013Conference paper, Published paper (Refereed)
Abstract [en]

Project-based education in combination with problem based learning has been very successful, and has contributed to the popularity of engineering design education among students at technical universities. The close connection to industrial problems by the use of industry-connected projects has boosted this popularity still further and to get an insight of future working environments after graduation is very inspiring for the students.

The curriculum of the Machine Design capstone course at KTH Department of Machine Design covers the whole process from idea generation to manufacturing and testing a final prototype. A major part of the course consists of project work where students develop a product prototype in close cooperation with an industrial partner or with a research project at the department. This means that a major part of the course uses project-based learning as a teaching strategy. In addition, a model-based design methodology is introduced which enables the students to evaluate and "experience" many different behaviors of the product using digital models in a virtual environment. In this way, students can see that many undesirable concepts and flaws can be avoided even before a prototype is manufactured.

This paper evaluates the use and learning outcome of model-based design in a capstone course in the Engineering Design MSc program at KTH Department of Machine Design. The approach has been used during a period of three years and the effect on the students' learning has been evaluated by a questionnaire after each course. I this paper we compare the results of these questionnaires and discuss implications and general conclusions about this learning approach.

National Category
Educational Sciences Mechanical Engineering
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-179043 (URN)10.1115/DETC2015-47276 (DOI)000379883900061 ()2-s2.0-84979053444 (Scopus ID)978-0-7918-5710-6 (ISBN)
Conference
ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Boston, MA, AUG 02-05, 2015
Note

QC 20151210

Available from: 2015-12-09 Created: 2015-12-09 Last updated: 2016-08-23Bibliographically approved
Khan, S., Andersson, K. & Wikander, J. (2015). Jacobian Matrix Normalization - A Comparison of Different Approaches in the Context of Multi-Objective Optimization of 6-DOF Haptic Devices. Journal of Intelligent and Robotic Systems, 79(1), 87-100
Open this publication in new window or tab >>Jacobian Matrix Normalization - A Comparison of Different Approaches in the Context of Multi-Objective Optimization of 6-DOF Haptic Devices
2015 (English)In: Journal of Intelligent and Robotic Systems, ISSN 0921-0296, E-ISSN 1573-0409, Vol. 79, no 1, p. 87-100Article in journal (Refereed) Published
Abstract [en]

This paper focuses on Jacobian matrix normalization and the performance effects of using different criterion and techniques. Normalization of the Jacobian matrix becomes an issue when using kinematic performance indices and the matrix contains elements with non-homogenous physical units, i.e. representing both translational and rotational motions. Normalization is necessary in multi objective optimization if kinematic performance indices are used based on the full Jacobian matrix. Different methods have been proposed in literature for defining a scaling factor used to normalize the Jacobian. Based on a comparison of a few of these methods, we conclude that it is better to have the scaling factor as a design variable in the multi objective optimization. However, as an alternative, a new scaling factor is proposed based on the relationship between linear actuator motion range in joint space and rotational end effector motion in task space, a proposal underpinned by simulation, analysis and comparison of optimization results using existing normalization techniques. For optimization, performance indices for workspace, kinematic sensitivity, device isotropy and inertia are considered. To deal with the multi-objective optimization problem, genetic algorithms are employed together with a normalized multi-objective optimization function. The performances of different device configurations (depending on the normalization method and the global isotropy index used) are presented in this article.

Keywords
Jacobian normalization, Haptics, Performance indices, Design optimization
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-169949 (URN)10.1007/s10846-014-0147-1 (DOI)000355859000007 ()2-s2.0-84930484008 (Scopus ID)
Note

QC 20150626

Available from: 2015-06-26 Created: 2015-06-25 Last updated: 2017-12-04Bibliographically approved
Sun, X., Andersson, K. & Sellgren, U. (2015). Towards a Methodology for multidisciplinary Design Optimization of Haptic Devices. In: Proceedings of the ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2015: . Paper presented at ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2015,August 2-5, 2015, Boston, Massachusetts, USA.
Open this publication in new window or tab >>Towards a Methodology for multidisciplinary Design Optimization of Haptic Devices
2015 (English)In: Proceedings of the ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2015, 2015Conference paper, Published paper (Refereed)
Keywords
Haptics, optimization
National Category
Engineering and Technology Applied Mechanics
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-179047 (URN)10.13140/RG.2.1.4746.1203 (DOI)000379883800035 ()2-s2.0-84978958094 (Scopus ID)
Conference
ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2015,August 2-5, 2015, Boston, Massachusetts, USA
Note

QC 20151210

Available from: 2015-12-09 Created: 2015-12-09 Last updated: 2017-11-08Bibliographically approved
Ahmad, A., Andersson, K. & Sellgren, U. (2014). A deterministic and probabilistic approach for robust optimal design of a 6-DOF haptic device. In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference--2013: Volume 3 B, 2013. Paper presented at ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC/CIE 2013; Portland, OR; United States; 4 August 2013 through 7 August 2013 (pp. V03BT03A032). ASME Press
Open this publication in new window or tab >>A deterministic and probabilistic approach for robust optimal design of a 6-DOF haptic device
2014 (English)In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference--2013: Volume 3 B, 2013, ASME Press, 2014, p. V03BT03A032-Conference paper, Published paper (Refereed)
Abstract [en]

This work suggests a two-stage approach for robust optimal design of 6-DOF haptic devices based on a sequence of deterministic and probabilistic analyses with a multi-objective genetic algorithm and the Monte-Carlo method. The presented model-based design robust optimization approach consider simultaneously the kinematic, dynamic, and kinetostatic characteristics of the device in both a constant and a dexterous workspace in order to find a set of optimal design parameter values for structural configuration and dimensioning. Design evaluation is carried out based on local and global indices, like workspace volume, quasi-static torque requirements for the actuators, kinematic isotropy, dynamic isotropy, stiffness isotropy, and natural frequencies of the device. These indices were defined based on focused kinematic, dynamic, and stiffness models. A novel procedure to evaluate local indices at a singularity-free point in the dexterous workspace is presented. The deterministic optimization approach neglects the effects from variations of design variables, e.g. due to tolerances. A Monte-Carlo simulation was carried out to obtain the response variation of the design indices when independent design parameters are simultaneously regarded as uncertain variables. It has been observed that numerical evaluation of performance indices depends of the type of workspace used during optimization. To verify the effectiveness of the proposed procedure, the performance indices were evaluated and compared in constant orientation and in dexterous workspace.

Place, publisher, year, edition, pages
ASME Press, 2014
Keywords
Computer aided design, Computer simulation, Intelligent systems, Kinematics, Optimization, Stiffness, Uncertainty analysis, Deterministic and probabilistic approaches, Deterministic optimization, Monte-Carlo simulations, Multi-objective genetic algorithm, Optimal design parameters, Probabilistic analysis, Robust Optimal Design, Structural configurations, Optimal systems
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-146960 (URN)10.1115/DETC2013-13005 (DOI)000362380400032 ()2-s2.0-84896952690 (Scopus ID)978-0-7918-5589-8 (ISBN)
Conference
ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC/CIE 2013; Portland, OR; United States; 4 August 2013 through 7 August 2013
Note

QC 20140618

Available from: 2014-06-18 Created: 2014-06-18 Last updated: 2015-11-04Bibliographically approved
Ahmad, A., Kjell, A. & Sellgren, U. (2014). A model-based and simulation-driven methodology for design of haptic devices. Mechatronics (Oxford), 24(7), 805-818
Open this publication in new window or tab >>A model-based and simulation-driven methodology for design of haptic devices
2014 (English)In: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 24, no 7, p. 805-818Article in journal (Refereed) Published
Abstract [en]

High precision and reliable haptic devices are highly complex products. The complexity that has to be carefully treated in the design process is largely due to the multi-criteria and conflicting character of the functional and performance requirements. These requirements include high stiffness, large work-space, high manipulability, small inertia, low friction, high transparency, as well as cost constraints. The requirements are a basis for creating and assessing design concepts. Concept evaluation relies to a large extent on a systematic usage of kinematic, dynamic, stiffness, friction, and control models. The design process can benefit from a model-based and simulation-driven approach, where one starts from an abstract top-level model that is extended via stepwise refinements and design space exploration into a detailed and integrated systems model that can be physically realized. Such an approach is presented, put in context of the V-model, and evaluated through a test case where a haptic device, based on a Stewart platform, is designed and realized. It can be concluded, based on simulation and experimental results that the performance of this deterministically optimized haptic device satisfies the stated user requirements. Experiences from this case indicate that the methodology is capable of supporting effective and efficient development of high performing haptic devices. However, more test cases are needed to further validate the presented methodology.

Keywords
Estimation, Haptic device, Model-based design
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-144179 (URN)10.1016/j.mechatronics.2014.01.006 (DOI)000344825700006 ()2-s2.0-84908117938 (Scopus ID)
Note

QC 20141211

Available from: 2014-04-11 Created: 2014-04-11 Last updated: 2017-12-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6692-2794

Search in DiVA

Show all publications