Virtual Rheological Objects for Visual and Haptic Presentation

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This research establishes fundamental technologies for visual and haptic presentation of rheological objects. Rheological objects such as biological tissues and foods show both viscoelastic and plastic nature in their deformation. In this research, we first established a particle-based modeling of rheological objects. Introducing topology maintaining and volumatic effects, we have succeeded a stable computation of rheological deformation in the particle-based modeling. Second, we realized a logical circuit to compute the rheological deformation using an FPGA. Implementing the computation of rheological deformation on an FPGA(Field Programmable Gate Array), we realized almost 100 times faster computation than PC computation. Thirdly, we established a calibration method to identify model parameters in a particle-based model. We constructed a system to measure realtime deformation of a rheological object and pressure distribution on it to identify the model parameters based on the measurements. Next, we investigated another particle-based modeling based on continua mechanics. We stably computed the deformation of uncompressive objects where Poisson's ratio is equal to 0.5 using the CSM (Constraint Stabilization Method).This research is summarized as 1) computation of large rheological deformation based on particle-based modeling, 2) realtime deformation computation using FPGA (Field Programmable Gate Array), 3) realtime deformation measurement using a laser range finder and a tactile sensor, and 4) identification of model parameters by randomized algorithm. Based on these results, simulation of deformation where compression ratio is 10%, video-frame rate computation of a particle-based model with over 1000 particles, and model identification with error within 10%.