Development of Visual Haptic Display Using Flexible Sheet

开发了一种基于柔性片的虚拟软物体视觉触觉显示系统。像橡胶这样的柔性薄片在受到拉伸时会变硬；它一松开就变软了。因此，如果改变施加在薄片上的偏置张力，当用户直接触摸薄片时，可以感受到不同的顺应性。我们开发了一种触觉显示器，它由两个机械手和一个半透明的柔性片组成；纸的两面都固定在机械手上。我们实现了一种通过使用机械手拉片来改变片材顺应性的控制方法。然后我们测量了薄片的力-位移曲线。结果表明，该系统可以通过改变偏置张力来产生可变的片材柔度。我们还开发了一种移动薄片的操纵器的控制方法，使其在用户手指触摸的点上可能是虚拟物体的切平面。我们做了一个主动触摸的实验：用手指触摸一个更真实的圆柱体。作为一种视觉显示，我们提出了一种将变形的虚拟软物体的三维CG图像从其背面直接投影到薄片上的方法。首先，通过立体摄像机测量用户手指的三维位置，并获得虚拟物体被推的深度。其次用有限元法计算了物体的变形。第三，将变形物体的三维CG图像从其背面直接投影到薄片上。然后用户通过立体眼镜看到纸上的虚拟物体。当用户使用上述触觉显示器触摸虚拟物体时，投影在薄片上的CG图像会因薄片的移动和被推薄片的凹陷而发生扭曲。因此，我们开发了一种纠正这种CG图像失真的方法。我们从用户的角度对校正后的图像进行了精度评估，并展示了该图像校正的有效性。通过将上述的触觉显示和视觉显示相结合，用户可以看到虚拟软物体的三维CG图像并直接触摸它。他们可以通过推来感受物体的顺应性，通过主动触摸来感受物体的形状。少

A visual haptic display system using flexible sheet for presenting virtual soft objects is developed.1.A flexible sheet such as rubber becomes hard when it is tensioned; it becomes soft when loosened. Hence, if the bias tension applied to the sheet is changed, users can feel different compliance when they touch the sheet directly. We developed a haptic display which consists of two manipulators and one translucent flexible sheet; both sides of the sheet are fixed to the manipulators. We implemented a control method of varying the sheet compliance by pulling the sheet using the manipulators. Then we measured the force-displacement curve of the sheet. As a result we showed that this system can generate variable sheet compliance by changing the bias tension. We also developed a control method for the manipulators of moving the sheet so that it may be a tangential plane of a virtual object at the point which a user's finger touches. We performed an experiment of active touch: stroking a vi … More rtual cylinder with a finger.2.As a visual display we proposed a method of projecting three dimensional CG image of a deformed virtual soft object directly on the sheet from its backside. First the three-dimensional position of a user's finger is measured by stereo cameras and obtained how deep the virtual object is pushed. Second the deformation of the object is calculated by finite element method. Third the three dimensional CG image of the deformed object is projected directly on the sheet from its backside. Then the user sees the virtual object on the sheet through stereoscopic glasses. When the user touches the virtual object using the above-mentioned haptic display, the CG image projected on the sheet is distorted by the movement of the sheet and the depression of the pushed sheet. Thus we developed a method of correcting this CG image distortion. We evaluated the accuracy of the corrected image seen from the user's viewpoint and showed the effectiveness of this image correction.3.By integrating the above-mentioned haptic display and visual display, the users can see the three-dimensional CG image of a virtual soft object and touch it directly. They can feel the compliance of the object by pushing and the shape of the object by active touch. Less