■T.Takahashi, K.Konno, J.Sone, Y.Tokuyama, O. Harabi: Haptic Interaction with Complex Objects Based on Local-domain Forces and Distributed Collision Detection Approach, The Journal of Art and Science, Vol.9, No.2, pp.38-48, (2010).

Abstract:
his paper presents a virtual haptic interaction system that employs a distributed collision detection algorithm using PC-cluster. The system achieved very fast collision detection with complex objects that have a large number of polygons and forces were applied in the local domain of the collision area. Using PC-cluster to calculate collision improves the response significantly. In addition, a pseudo force generation approach is proposed to smooth the force feedback produced in the haptic loop.

■T.Takahashi, K.Konno, O. Harabi, Y. Tokuyama: STUDY ON FORCE FEEDBACK RENDERING TECHNIQUE FOR LOCAL DOMAIN USING PRESSURE-SENSOR DEVICE, Proc. of IWAIT2010, (2010).

Abstract:
Building a virtual reality (VR) system becomes easier and affordable with the availability of low-cost and high performance hardware. The VR technology can be beneficial for applications in various fields, such as medical engineering, education, video games, and other graphic activities. One of the potential applications is the virtual touching of an object that cannot be actually touched. For instance, it is impossible to touch cultural assets exhibited in historical museums. If it becomes possible to pick them up in order to see the part where visitors could not see, they will get much more information from the assets, compared to the case when they just look at them. One solution is to use haptic technology that enables the feeling of touching virtual objects. To achieve realistic force rendering in order to provide a realistic sense of touch, it is necessary to approximate the force feedback to the actual world. In previous studies, force feedback was presented by using a spring-damper model, for which a linear spring was connected to a viscosity attenuation device. Although the spring-damper model is versatile to present force feedback, it is difficult for the spring-damper model to present realistic texture of hard materials, such as a rigid body. In this paper, we examine force feedback rendering based on measurement data obtained by measuring the texture of an object with a pressure-sensor device.

■T. Takahashi, K. Wada, K. Konno, J. Sone. Y. Tokuyama: A Study on Force Feedback Presentation System for Local Domain Based on Distributed Collision Detection, Proc. of IWAIT2009, 2009.

Abstract:
Constructing virtual reality (VR) system has become easy and possible since low-cost and high-performance hardware becomes popular. The VR technology is expected for various kinds of application such as virtual museum, medical engineering, education, video games and other graphic activities. A lot of element technologies to construct such VR environments have been studied, while integrating the element technologies still costs much. This problem arises because response speed of ordinary computers is very slow and expensive computers must be prepared to integrate the element technologies. One of the solutions about the cost and the processing speed is to decentralize element technologies. We build a VR system to disperse a large amount of calculation to a PC cluster and to integrate the calculation results. In addition, the client PC generates multiple threads by using thread programming. By dispersing the processing loops into two threads, the force feedback presentation thread and the distributed collision detection thread, the problem of response speed will be solved. It is difficult, however, to execute smooth force feedback presentation in real time because the update rate of distributed collision detection is more than 20 times slower than the rate of the force feedback presentation thread. In this paper, we have studied the virtual touching system that uses the collision detection with a PC cluster. Our system realizes high-speed collision with a complex object that has a large number of polygons and presents force feedback in a local domain of collision. Using a PC cluster to calculate collision improves response speed. In addition, we construct a system to present smooth force feedback by generating artificial force feedback in the force feedback presentation thread, where the amount of calculation is small and processing speed is high.

■K. Wada, K. Konno, J. Sone, Y. Tokuyama: An Investigate of Calculation Performance to Construct A VR System Based on Distributed Collision Detection, Proc. of IWAIT2007, 2007.

Abstract:
Constructing virtual reality (VR) system has become easy and possible since low-cost and high-performance hardware becomes popular. The VR technology is expected for various kinds of application such as virtual museum, medical engineering, education, video games and other graphic activities. One of the expected applications is virtual touching on an object that we cannot touch usually. For instance, it is impossible to touch cultural assets exhibited in historical museums. If it becomes possible to pick them up in order to see the part where visitors could not see, they will get much more information from the assets, compared to the case when they just look at them. One solution is to construct the system enabling to touch an object virtually by using the VR technology. Previously a lot of basic technologies for the VR system construction have been researched: collision detection using the Binary Space Partitioning (BSP) tree, naked-eye stereoscopic devices or physical simulation for the sense of force display using a haptic device. With such a lot of basic technologies, however, few practical systems have been established to integrate the basic technologies in some lower-cost PC environment. All of these basic technologies require high-speed calculation environment and the calculation cost is massive to construct the VR system that integrates the technologies. Therefore, it is difficult for one computer to enable 3D model drawing, simulation and sensing in real time. If a VR system distributes massive calculation cost into two or more computers, the problem of the response may be solved. In this paper, we investigate the calculation performance to construct the VR system that uses the collision detection with a PC cluster. Our technique realizes collision with a complex object that has a large number of polygons at high speed. Quick response upon collision is realized as a PC cluster processes collision calculation when the model of a hand is moved using a haptic device. The PC cluster used in this research can be easily constructed since they use the Windows OS capabilities. As varying the number of contacts with an object, the time of collision calculation is measured, so that the effectiveness of distributed processing with a PC cluster is shown.