オブジェクト座標系に基づいた絶対位置制御法

Three-dimensional ankle joint moments were calculated in two separate coordinate systems, from 18 healthy men during the stance phase of walking, and were then compared. The objective was to determine the extent of differences in the calculated moments between these two commonly used systems and their impact on interpretation. Video motion data were obtained using skin surface markers, and ground reaction force data were recorded from a force platform. Moments acting on the foot were calculated about three orthogonal axes, in a global coordinate system (GCS) and also in a segmental coordinate system (SCS). No differences were found for the sagittal moments. However, compared to the SCS, the GCS significantly (p < .001) overestimated the predominant invertor moment at midstance and until after heel rise. It also significantly (p < .05) underestimated the late stance evertor moment. This frontal plane discrepancy was attributed to sensitivity of the GCS to the degree of abduction of the foot. For the transverse plane, the abductor moment peaked earlier (p < .01) and was relatively smaller (p < .01) in the GCS. Variability in the transverse plane was greater for the SCS, and attributed to its sensitivity to the degree of rearfoot inversion. We conclude that the two coordinate systems result in different calculations of nonsagittal moments at the ankle joint during walking. We propose that the body-based SCS provides a more meaningful interpretation of function than the GCS and would be the preferred method in clinical research, for example where there is marked abduction of the foot.

Optimal spatial orientation which minimizes bias error in model-based radiostereometric analysis for a cementless tibial baseplate is not aligned with the anatomic orientation defined by the global coordinate system.

A coupled mode equation for two nonparallel dielectric waveguides is rigorously derived from the Lorentz reciprocity theorem. the waveguides are located close to each other. Two local coordinate systems are introduced to present an intrinsic mode function. A global coordinator system also is employed to solve the coupled mode equation. As a numerical example, a coupling system consisting of two dielectric disks with different radii is analyzed. the coupled mode equation for whispering gallery modes propagating along a circumference of the disks is solved numerically in the global coordinate system. Eigenvalues of the whispering gallery modes are complex numbers because of radiation and dielectric losses. As a result, electric field distribution and the coupling coefficient around the coupling system are obtained quantitatively.

Stability analysis of milling process by combining the gyroscopic effect with the symmetry and runout of the cutter

We consider composite materials consisting of continuous or discontinuous fibers embedded in a matrix. Such a composite is heterogeneous, and the properties vary from point to point. On a scale that is large with respect to the fiber diameter, the fiber and matrix properties may be averaged, and the material may be treated as homogeneous. This assumption, commonly employed in macromechanical analyses of composites, is adopted here. Hence, the material is considered to be quasi-homogeneous, which implies that the properties are taken to be the same at every point. These properties are not the same as the properties of either the fiber or the matrix but are a combination of the properties of the constituents. In this chapter, equations are presented for calculating the displacements, stresses, and strains when the structure undergoes only small deformations and the material behaves in a linearly elastic manner. Continuous fiber-reinforced composite materials (and structures made of such materials) often have easily identifiable preferred directions associated with fiber orientations or symmetry planes. It is therefore convenient to employ two coordinate systems: a local coordinate system aligned, at a point, either with the fibers or with axes of symmetry, and a global coordinate system attached to a fixed reference point (Fig. 2.1). In this book the local and global Cartesian coordinate systems are designated respectively by x 1 , x 2 , x 3 and the x, y, z axes.

We consider the spatial localization of nodes in a network, based on measurements of their relative position with respect to their neighbors. These measurements include the nodes' relative positions in a global coordinate system, their distances, or their pseudo ranges. We show that the maximum likelihood estimator associated with these localization problems can be viewed as a constrained optimization problem with a specific structure and provide a distributed algorithm to solve it. Under appropriate assumptions, it is shown that the maximum likelihood estimates are locally asymptotically stable equilibrium points of the proposed algorithm. As a case study, we consider a range-based localization problem and present simulation results to evaluate the algorithm.

Mobile visual detecting system with a catadioptric vision sensor in pipeline

DGN95 is a static geospatial reference system, in which the change in the value of coordinates towards time as a result of tectonic plate movement and deformation of the earth’s crust, is not considered. Changes in the value of coordinates towards time need to be considered in defining a geospatial reference system for the territory of Indonesia. This is because the territory of Indonesia is located between several tectonic plates which are very dynamic and active. This area of IndoneFor this reason, SRGI2013 was born, a national coordinate system that was consistent and compatible with the global coordinate system. SRGI considers changes in coordinates based on time functions. Problems arise when the coordinates of the old pillar still use the DGN95 datum reference system. Many published maps or geodetic control network use the old coordinate system, then the mapping user has difficulty getting the conversion of coordinates change aforesaid. The purpose of this study is to produce coordinate transformation parameters to change the coordinates of the old datum (DGN95) into coordinates in the SRGI2013 datum. The results of the transformation parameters resulted are used to change coordinates that are still in the old datum. In addition to making it easier for users to transform coordinates. The coordinate transformation method used uses the 3-dimensional coordinate transformation of the Bursa-Wolf model (7 parameters) and the Affinity model (10 parameters).

We consider a distributed system consisting of autonomous mobile computing entities called robots moving in the three-dimensional space (3D-space). The robots are anonymous, oblivious, fully-synchronous and have neither any access to the global coordinate system nor any explicit communication medium. Each robot cooperates with other robots by observing the positions of other robots in its local coordinate system. One of the most fundamental agreement problems in 3D-space is the plane formation problem that requires the robots to land on a common plane, that is not predefined. This problem is not always solvable because of the impossibility of symmetry breaking. While existing results assume that the robots agree on the handedness of their local coordinate systems, we remove the assumption and consider the robots without chirality. The robots without chirality can never break the symmetry consisting of rotation symmetry and reflection symmetry. Such symmetry in 3D-space is fully described by 17 symmetry types each of which forms a group. We extend the notion of symmetricity [Suzuki and Yamashita, SIAM J. Compt. 1999] [Yamauchi et al., PODC 2016] to cover these 17 symmetry groups. Then we give a characterization of initial configurations from which the fully-synchronous robots without chirality can form a plane in terms of symmetricity.

Automatic concrete cracks detection and mapping of terrestrial laser scan data

Multi-agent formation control is an important part of distributed perception and cooperation, which is convenient to complete various complex tasks and would be a key research direction in the future. This paper reviews the corresponding problems of formation control and the existing centralized and distributed formation control strategies. In particular, we discuss four types of distributed formation control methods based on position and displacement in the global coordinate system and distance and bearing in the nonglobal coordinate system, respectively. Moreover, this paper analyzes affine formation which does not require the global coordinate system. Combined with the current practical applications of multi-agent systems, the latest research for the formation control of the unmanned aerial vehicle (UAV), unmanned ground vehicle (UGV), unmanned surface vehicle (USV) and autonomous underwater vehicle (AUV) is given. Finally, the challenges and opportunities in this burgeoning field are discussed.

Conservation laws of the J k-vector for microcrack damage in piezoelectric materials

We present an approach to quantifying the off-axis stiffness properties of parallel compliant mechanisms used in the design of mobile millirobots. By transforming the stiffness of individual flexure elements and rigid links comprising a compliant mechanism into a global coordinate system, we enable the formulation of an equivalent mechanism stiffness. Using that stiffness in concert with an energy-based performance metric, we predict the performance of a compliant mechanism subjected to a prescribed set of forces in the global coordinate system. We analyze a flexure-based Sarrus linkage and use the performance metric to improve the design by adding topological redundancy. Finally, our approach is experimentally validated by constructing and testing SCM Sarrus linkages in a variety of geometries and topologies and demonstrating agreement between the model and our experiments.

We propose a LiDAR point-based docking spot generation system for autonomous docking using point clouds from a low-density LiDAR sensor in berthing environments. The system consists of four key stages: scan matching, 3D object detection, long-term object perception, and docking spot generation. Scan matching estimates the unmanned surface vehicle’s position within the global coordinate system using scan-to-map matching. In the 3D object detection stage, high-quality point clouds are generated from low-density LiDAR data to enhance detection performance, and detected object information is transformed into the global coordinate system. In the long-term object perception stage, object information beyond the LiDAR’s field of view is stored on the map for continuous environmental perception. Finally, the docking spot generation stage employs an algorithm to generate valid docking spots. Experimental validation in real-world environments demonstrates that the proposed system achieves an average 3D mAP improvement of 23.38 percentage points across multiple detection architectures. Notably, for small object detection, the average 3D AP improvement reaches 38.12 percentage points, demonstrating significant effectiveness in challenging scenarios. These improvements enhance long-term perception, object management, and docking spot generation stability.

A novel distance estimation approach for 3D localization in wireless sensor network using multi dimensional scaling