This paper compares and analyzed the structures of social network of robotics researchers that are generated based on co-authorship relations in Journal of RSJ and IEEE/T-RO. It turns out that there are more structural holes in the network of IEEE/T-RO than the network of Journal of RSJ, and it needs more time to bridge over the structural holes. Based on the analysis, this paper proposes the strategies that Japanese researchers should take in the social network of international robotics researchers, and also, suggests the measures for research supporting agencies to promote the above strategies.
This paper presents a new wheel mechanism for the active-caster drive system. The active-caster provides omnidirectional mobility with no using free rolling mechanism. The original active-caster equips with an absolute encoder to detect a wheel orientation and two motors for driving wheel and steering axis independently. A computer system needs to detect an absolute wheel orientation and coordinate velocity components for wheel and steering drive to provide wheel motion in an arbitrary direction. To simplify the wheel control system, a new active-caster mechanism is proposed. A proposed active-caster system includes a ball transmission to distribute a traction velocity to wheel and steering axis mechanically without using an angle sensor or coordinated motor control. In this paper, kinematics of the proposed wheel mechanism is analyzed and mechanical condition for realizing the caster motion is derived. A kinematic model of the proposed active-caster mechanism with a ball transmission is analyzed and a mechanical condition for realizing caster motion is derived. Based on the kinematic model and the mechanical condition, computer simulations of the mechanism are performed. In the simulations, the active-caster shows successful caster motions with no sensor or computer system.
We developed the world's first hair-washing robot equipped with scrubbing fingers. This robot assists in washing hair in hospitals or care facilities, and allows liability relief of healthcare professionals or care workers and higher quality of life for patients or members in need of nursing care. It features the mechanical and control technology for touching someone gently on the head, for instance, the self-aligning mechanism and the cylindrical rack mechanism of its end effector, the parallel link mechanism of its pressing arm, and the compliance control for providing appropriate sense of pressure.
Quantitative assessment of forest resources is an important topic from the point of view of the absorption of greenhouse gases. This article presents two contrasting approaches to automatic detection of tree-trunks by fitting right cylinder models to 3D point clouds taken in real forest land as well as those synthesized for analysis purposes. Volumetric index of tree-trunks can be estimated by those model parameters. The first approach segments point cloud into overlapping local bounding boxes (windows) and cylinder models and terrain models are calculated in each window by nonlinear and linear least-square methods. This method secures the detection accuracy of tree-trunks by means of the rejection of false-positives through outlier detection and the avoidance of false-negatives through redundancy of search space. The second approach formulates the present problem as an engergy minimization and detects multiple cylinder models concurrently by a graph-cuts algorithm. Experimental results provide enough evidence of effectiveness of the proposed approaches.
In the paper, we construct human behavioral judgment model for collision avoidance when a person is walking and abruptly encounters another at an indoor blind corner. The judgment model includes tactics which take effect when a person encounters another using a mixed strategy of game theory. In addition, we changed the human behavior caused by information uncertainty taking the distance to the other person into a formula using the Dempster-Shafer theory of evidence. Effectiveness of the developed judgment model was verified by a simulation. Based on such a model as to take human behavioral characteristics into account, robot navigation control is expected to realize safe and efficient operation even at blind corners of indoor aisle intersections that contain a high risk of collisions.
A method to solve a pose estimation problem, that is, the estimation of a rigid body transformation (in particular, a rotation matrix) that gives the best match between the registration of non-corresponding 3-D point sets is proposed. First, it is shown that the rotation matrix can be estimated by left singular vector matrices derived by the singular value decomposition of the given 3-D point sets. Next, it is shown that the rotation matrix between non-corresponding 3-D point sets whose number of elements is different can be found immediately using the proposed method by numerical simulations.
The purpose of this study is to perform a dynamic manipulation of a linear flexible object. As examples of the dynamic manipulation, shape controls and a dynamic knotting of a flexible rope are achieved by a high-speed robot arm. First, an entirely new strategy for dynamic manipulation of the flexible rope with the high-speed robot is introduced. The strategy is to manipulate the flexible rope with a high-speed motion. Moving the robot at high-speed, we assume that a dynamic deformation of the flexible rope can be obtained through algebraic calculations based on the robot motion. Based on this assumption, we propose a discrete deformation model of the flexible rope. As a result, we can obtain the robot trajectory from the desired rope configuration using the proposed model. Moreover, we discuss the validity of the proposed model based on the equation of motion of the flexible rope. Next, simulation results and experimental results of shape controls (rectangle and circle) are described. Finally, simulation result and experimental result of the dynamic knotting using a high-speed robot arm are shown as one application of the proposed method.