Ryo Furukawa

Development of a humanoid robot Saika

This article addresses the development of a light-weight, human-size and low-cost developing humanoid robot named Saika. Saika has a 2-DOF neck, two 5-DOF upper arms, a torso and a head. Several types of hands and forearms are developed. They are chosen depending upon the tasks to perform. The features of Saika are: (a) Saika as modularized to reduce the developing cost and to make maintenance easy, (b) the total weight of the head, the neck, the two upper arms and the torso is only eight kilograms and (c) most of the motors are installed inside the arms and the torso.

Dense 3D Reconstruction method using Coplanarities and Metric Constraints for Line Laser Scanning

In this paper, we propose a novel method to achieve both dense 3D reconstruction of the scene and estimation of the camera intrinsic parameters by using coplanarities and other constraints (e.g. orthogonalities or parallelisms) derived from relations between planes in the scene and reflected curves of line lasers captured by a single camera. In our study, we categorize coplanarities in the scene into two types: implicit coplanarities, which can be observed as reflected curves of line lasers, and explicit coplanarities, which are, for example, observed as walls of a building. By using both types of coplanarities, we can construct simultaneous equations and can solve them up to four degrees of freedom. To upgrade the solution to the Euclidean space and estimate the camera intrinsic parameters, we can use metric constraints such as orthogonalities of the planes. Such metric constraints are given by, for example, observing the corners of rectangular boxes in the scene, or using special laser projecting device composed of two line lasers whose laser planes are configured to be perpendicular.

Single colour one-shot scan using modified penrose tiling pattern

In this study, the authors propose a new technique to achieve one-shot scan using single colour and static pattern projector; such a method is ideal for acquisition of moving objects. Since projector–camera systems generally have uncertainties on retrieving correspondences between the captured image and the projected pattern, many solutions have been proposed. Especially for one-shot scan, which means that only a single image is required for shape reconstruction, positional information of a pixel of the projected pattern should be encoded by spatial and/or colour information. Although colour information is frequently used for encoding, it is severely affected by texture and material of the object and leads unstable reconstruction. In this study, the authors propose a technique to solve the problem by using geometrically unique pattern only with black and white colour that further considers the shape distortion by surface orientation of the shape. The authors technique successfully acquires high-precision one-shot scan with an actual system.

Dexterous Manipulations of the Humanoid Robot Saika

This article addresses the development of a humanoid robot named Saika and skillful manipulations performed by Saika. The developed humanoid robot Saika has a two-DOF neck, dual five-DOF upper arms, a torso and a head which consists of two eyes and two ears. Saika has humansize dimension and weighs eight kilograms. This article also presents three kinds of manipulations performed by Saika: (1) hitting a bounding ball, (2) grasping unknown objects by groping and (3) catching a thrown ball. Those tasks are chosen to study behavior-based movement control and intelligence.

Braided embeddings of contact 3‐manifolds in the standard contact 5‐sphere

In this paper we study embeddings of contact manifolds using braidings of one manifold about another. In particular we show how to embed many contact 3-manifolds into the standard contact 5-sphere. We also show how to obstruct braidings of one manifold about another using contact geometry.

Wide-Area Shape Reconstruction by 3D Endoscopic System Based on CNN Decoding, Shape Registration and Fusion

For effective in situ endoscopic diagnosis and treatment, dense and large areal shape reconstruction is important. For this purpose, we develop 3D endoscopic systems based on active stereo, which projects a grid pattern where grid points are coded by line gaps. One problem of the previous works was that success or failure of 3D reconstruction depends on the stability of feature extraction from the images captured by the endoscope camera. Subsurface scattering or specularities on bio-tissues make this problem difficult. Another problem was that shape reconstruction area was relatively small because of limited field of view of the pattern projector compared to that of the camera. In this paper, to solve the first problem, learning-based approach, i.e., U-Nets, for efficient detection of grid lines and codes at the detected grid points under severe conditions, is proposed. To solve the second problem, an online shape-registration and merging algorithm for sequential frames is proposed. In the experiments, we have shown that we can train U-Nets to extract those features effectively for three specimens of cancers, and also conducted 3D scanning of shapes of a stomach phantom model and a surface inside a human mouth, in which wide-area surfaces are successfully recovered by shape registration and merging.

Improvement of image quality by using viewpoint following in multi-layer light field display

Image qualities of multi-layer light field display depend on the size of viewpoint area. By dividing the light filed samples into subsets and reproducing the light field for each subset, the image quality is improved.