Localization is an important function for a mobile robot. In this research, a new localization method using a spherical stereo camera is proposed. Spherical stereo cameras are effective for motion estimation as they can visualize and measure all directions of the environment. Instead of using conventional sparse feature points, dense information of all pixels in images is used to estimate motion accurately. However, because of the wide field of view, the 3D measurement uncertainty is not uniform across the image. Hence, geometric uncertainty of every 3D point is calculated and used as weights to improve accuracy. Experiments show the effectiveness of using uncertainty information to increase the accuracy of motion estimation.
In the past very few papers have reported the interrelation between servo motor specifications and feed axes of machine tools. In the former paper “Study of the Moment of Inertia Ratio of Feed Axes of Machining Centers to Servo Motors", the interrelation between the moment of inertia ratio and the kinds of actual machining centers as well as their typical work pieces was studied. Based on this study, the interrelation between the moment of inertia ratio of machining center feed axes to servo motors and actual cutting results by a machining center is studied in this 2nd paper.
At first three groups of servo motors are prepared with the similar output torque but different moment of inertia. Then these three groups of servo motors are one after another installed in the same machining center, and real machining is carried out under the same cutting conditions. The results of this show that the servo motors with relatively low moment of inertia contribute to high cycle machining, while those with relatively high moment of inertia contribute to high precision and fine surface machining. These results are consistent with the ones in the former paper.
The task of the inverse kinematics is to find a set of joint angles so that the endpoint of the robot reaches to a goal point. However, in the conventional inverse kinematics methods, we often have a problem of singular position, in which we cannot find a solution due to numerical calculation even if it exists. Furthermore, inverse kinematics calculation costs greatly in a hyper redundant series robot with a massively large number of joints. Therefore, we need a singular position free and computation effective kinematics calculation method. A key idea in this paper is to determine a joint angle in a distributed manner. Each of the joints determines a displacement of its joint angle for contributing to the goal, when a goal and current position of the endpoint are given. Then the robot goes to a new posture by applying all the joint angles. We repeat the process again until it comes to the goal. This paper presents the development of a distributed forward and inverse kinematics method for the hyper redundant series robot. We have verified our method with a set of numerical experiments.
The present paper describes running tests of internal gears made of polyacetal. The results are analyzed on the basis of JIS B 1759 in order for their load capacity to be evaluated. As a result, polyacetal internal gears have much higher load capacity than external gears. Actual contact ratios, whose calculations include effects of tooth deformation, and smaller meshing losses in internal gears than external gears cannot explain the reason. In addition, the present paper presents key points to be considered in the design of the jig for internal gears to be tested.
Normally, tool path is generated by geometric calculation between a model and the cutting tool. However, as the number of curved surfaces increases, the number of polyhedrons increases, so a calculation time becomes enormous. In past research, the calculation method using offset surface generation and the parallel processing function of GPU were proposed to solve this problem. However, these methods didn’t consider error due to the approximation process and increase in memory usage. In the previous research, the authors defined the offset elements as three geometric shapes of offset polygons, cylinders, and spheres, and updated the intersection point between the z axis and them in the height direction to generate accurate cutter locations. This paper proposed a new calculation algorithm to improve computational time for the proposed path generation process. In this research, in order to use the GPU efficiently, the reference order of the offset elements is rearranged in the scanning line direction. Then, it is divided into several groups according to the size of the offset elements. By applying these methods, it is possible to generate tool paths with high precision and high speed for large scale discrete shapes.