Publications Search Results

Now showing 1 - 6 of 6
  • Publication
    Light scattering in poly(vinyl alcohol) hydrogels reinforced with nanocellulose for ophthalmic use
    ( 2017)
    Tummala, G.K.
    ;
    Felde, N.
    ;
    Gustafsson, S.
    ;
    Bubholz, A.
    ;
    Schröder, S.
    ;
    Mihranyan, A.
    Scattering of ophthalmic devices is a complex phenomenon involving both surface and bulk light-material interactions. In this work, light scattering of nanocellulose reinforced PVA hydrogels contact lenses for ophthalmic applications was investigated. Optical microscopy, fluorescence microscopy and atomic force microscopy (AFM) techniques were used for ultrastructure characterization. Further, 3D angle resolved light scattering measurements in the visible spectral range were performed using a BTDF (bidirectional transmittance distribution function) sensor to quantify the scattered light. Surface and bulk scattering properties were discerned using white light interferometry. Total scatter levels ranging from 3% to 40% were observed depending on the hydrogel composition. The most critical factor affecting the light scattering properties in nanocellulose-reinforced PVA hydrogels was related to the state of hydration of the hydrogels, which is critical to maintain visual acuity of ophthalmic devices.
  • Publication
    Controller hierarchies for efficient virtual ergonomic assessments of manual assembly sequences
    ( 2016)
    Mardberg, P.
    ;
    Yan, Y.
    ;
    Bohlin, R.
    ;
    Delfs, N.
    ;
    Gustafsson, S.
    ;
    Carlson, J.S.
    A novel framework for manikin motion planning has been implemented to reduce the time needed to perform virtual ergonomic assessments of manual assembly sequences. The user feeds high level instructions into a hierarchical controller system. Depending on the state of the manikin and the objects in the environment, the controllers compute a sequence of low level instructions interpreted as path planning instances for the manikin. The result is automatically generated collision-free and ergonomically sound motions that accomplish the assembly tasks. The framework is demonstrated on relevant cases from the industry and the reduction in manual simulation preparation time is proven.
  • Publication
    Using a formal high-level language and an automated manikin to automatically generate assembly instructions
    ( 2014)
    Mårdberg, P.
    ;
    Carlson, J.S.
    ;
    Bohlin, R.
    ;
    Delfs, N.
    ;
    Gustafsson, S.
    ;
    Högberg, D.
    ;
    Hanson, L.
    This paper presents an approach to automatically generate predetermined motion time system (PMTS) based assembly instruction lists from simulations within digital human modelling (DHM) software. A formal high-level instruction language is used to instruct an automated manikin to perform assembly operations. The manikin, the language and the assembled objects are composed into a discrete model. In a post-computational step, the model is used to construct PMTS instruction lists by mapping the manikin motions, assembled objects and the language instructions onto a set of PMTS keywords. The described approach is implemented in the DHM software IMMA and tested on industrial cases of manual assembly in the automotive industry.
  • Publication
    Using a formal high-level language to instruct manikins to assemble cables
    ( 2014)
    Mårdberg, P.
    ;
    Carlson, J.S.
    ;
    Bohlin, R.
    ;
    Delfs, N.
    ;
    Gustafsson, S.
    ;
    Hanson, L.
    In this paper, a formal high-level language is used to generate simulations where a manikin assembles flexible cables. The language generates assembly instructions for the manikin, which automatically performs the corresponding assembly motion with as good ergonomic as possible. Due to weight, stiffness and narrow regions, it may be difficult to perform an assembly of the cable. Our approach allows us to verify that it may be performed in an ergonomically sound way. The generated instructions are formally verified to ensure that assembly order is held and to prevent erroneous assembly states. The simulations have been made on industrial test cases.
  • Publication
    Automatic creation of manikin motions affected by cable forces
    ( 2014)
    Delfs, N.
    ;
    Bohlin, R.
    ;
    Gustafsson, S.
    ;
    Mårdberg, P.
    ;
    Carlson, J.S.
    Effective simulation of manual assembly operations considering ergonomic load and clearance demands requires detailed modeling of human body kinematics and motions, including balance and response to external forces. In this paper we address the interaction of humans with flexible objects. By incorporating detailed physics simulation of flexible objects into the creation of ergonomically feasible human motions, we are able to ergonomically assess manual assembly operations involving cables and hoses. The method is implemented and demonstrated on a challenging operation taken from the automotive industry; a wiring harness assembly.
  • Publication
    Resource sharing in wireless networks: The SAPHYRE approach
    ( 2010)
    Jorswieck, E.A.
    ;
    Badia, L.
    ;
    Fahldieck, T.
    ;
    Gesbert, D.
    ;
    Gustafsson, S.
    ;
    Haardt, M.
    ;
    Ho, K.-M.
    ;
    Karipidis, E.
    ;
    Kortke, A.
    ;
    Larsson, E.G.
    ;
    Mark, H.
    ;
    Nawrocki, M.
    ;
    Piesiewicz, R.
    ;
    Römer, F.
    ;
    Schubert, M.
    ;
    Sykora, J.
    ;
    Trommelen, P.
    ;
    Ende, B.D. van
    ;
    Zorzi, M.
    Physical resource sharing between wireless operators and service providers is necessary in order to support efficient, competitive, and innovative wireless communication markets. By sharing resources, such as spectrum or infrastructure, which are usually exclusively allocated interference is created on the physical layer. Therefore, the economic gains, regulatory overhead, and engineering efforts need to be addressed by a consolidated cross-layer approach. This paper describes briefly the approach taken by the EU FP7 project SAPHYRE.