Body Coordinate System Research Articles

Three-dimensional analysis of relationship between relative orientation and motion modes

Target motion modes have a close relationship with the relative orientation of missile-to-target in three-dimensional highly maneuvering target interception. From the perspective of relationship between the sensor coordinate system and the target body coordinate system, a basic model of sensor is stated and the definition of relative angular velocity between the two coordinate systems is introduced firstly. Then, the three-dimensional analytic expressions of relative angular velocity for different motion modes are derived and simplified by analyzing the influences of target centroid motion, rotation around centroid and relative motion. Finally, the relationships of the relative angular velocity directions and values with motion modes are discussed. Simulation results validate the rationality of the theoretical analysis. It is demonstrated that there are significant differences of the relative orientation in different motion modes which include luxuriant information about motion modes. The conclusions are significant for the research of motion mode identification, maneuver detection, maneuvering target tracking and interception using target signatures.

Dissociating position and heading estimations: Rotated visual orientation cues perceived after walking reset headings but not positions

This project examined the roles of idiothetic cues due to individuals’ movement and allothetic cues independent of individuals’ movement in individuals’ estimations of their position and heading during locomotion. In an immersive virtual environment, participants learned the locations of five objects and then moved along two legs of a path before positioning the origin and the objects. Participants’ estimations of their test position and their test heading were calculated based on the responded objects’ locations, using a method of dissociating position estimation and heading estimation developed in this project. Results showed that when a conflicting visual orientation cue was presented after walking, participants relied on the allothetic cues (i.e., the visual orientation cue) for their heading estimation, but on idiothetic cues for their position estimation. These results indicate that after participants updated their position in terms the origin of the path (homing vector) via path integration, they estimated their heading. These results are inconsistent with the theoretical models stipulating that homing vectors are specified in terms of participants’ body coordinate systems, but are consistent with the models stipulating that both homing vectors and participants’ heading are specified in terms of a fixed reference direction in the environment.

A Motion Correction Technique for Laser Scanning of Moving Objects

The fundamental limitation for laser scanning of an object is that the object should be stationary. In this letter, we propose a novel technique for obtaining 3-D point cloud of a moving object by applying motion correction, so that the point cloud is correct in relative and absolute sense, and represents the true shape of the scanned object. In the proposed technique, a laser scanner is used to scan an object which is mounted with a GPS/IMU system and stationed at a distance from the scanner. The object is put in continuous motion (in a limited area) which may be linear, nonlinear, rotational, or of random type. The point cloud collected by the laser scanner is combined with the position and orientation information of the moving object to transform the whole point cloud into a new coordinate system, called object body coordinate system (OBCS), which is fixed to the object. This is realized, first by determining the relationship between an inertial measurement unit (IMU)body coordinate system and the OBCS, and then by using this relation to convert the coordinates of object measured in global coordinate system through laser scanner into the OBCS. Prior to this, the laser scanner is oriented to measure coordinates in global coordinate system. This letter first presents a complete theoretical background of the proposed method for a general case, and then outlines some simplified cases as encountered in practice. The proposed technique has applications in scanning objects that are not stable, e.g., a ship in a harbor.

Mechanical model of the perturbed motion of the earth with respect to the barycenter

A mechanical model of pole oscillations that fits the current views and the International Earth Rotation Service (IERS) data is constructed. The gravitational tidal torques due to the Sun and the Earth allowing for viscoelastic deformation of the Earth are considered to be the main perturbing factors. A bestfit, sixpara� metric mathematical model that takes into account the trend, annual oscillations, and Chandler oscilla� tions is constructed based on the IERS data using the spectral and dispersion analysis of a fairly complicated oscillation process. Major oscillation characteristics are determined using massive calculations. The inter� polation algorithm has been tested over long time scales, in particular, from 2000 through 2012. Algo� rithms for longscale prediction of oscillations at intervals of 60-900 days are proposed. 1. The dynamical theory of the rotation of the Earth with respect to the barycenter underlies many astrometric studies (1-5). It is known from astronom� ical observations (since the second half of the 19th century or, possibly, far back in the past) that the Earth's rotation axis changes its orientation over time with respect to both the body coordinate system and the inertial coordinate system. This implies that the poles and latitudes evolve within noticeable ranges over a year. Measurements indicate that components with strongly different frequency and amplitude character� istics are involved in the very complicated oscillation process. Thus, small oscillations of the angular veloc� ity vector in a specific Earthfixed coordinate system (the reference system) contain the major component with an amplitude that reaches 0.20

Analysis for Solar Array Radiation Receiving Characteristics on Stratospheric Airship

As one of the key technic of achieving high-altitude and long-time flight, the stratospheric airship energy system in stratosphere is always the important point but also very difficult. In this paper, the stratospheric airship geometry analysis as a starting point, through a series analysis as follow: the stratospheric airship surface mesh model, the sun vector, the relationship between the sun vector and the body coordinate system, and the solar radiation model, we have accomplished the characteristics analysis of the radiation receiving on stratospheric airship. The analysis result show that: Although different flight direction corresponding to different distribution of light intensity, the light changes from sunrise to sunset is symmetrical when the stratospheric airship on the condition of level flight. Airship for east heading of region resides, the maximum energy can be obtained when the solar array laying in the installation of 0 β π / 4. With the changing of heading angle and pitch angle, the radiation receiving of the solar array can also transform, but the influence of pitch angle greater than heading angle.

Debiased Converted Measurements Kalman Filter Algorithm for Motion Parameter Estimation

The directional warhead of ATBM missile requires accurate initiation delay time and the initiating direction to obey effective damage for TBM, which needs to estimate the relative motion parameters to improve the accuracy. A debiased converted measurement Kalman Filter is presented and used for the estimation of TBMs position in body coordinate system of ATBM missile and the relative velocity. Results of simulation shows that this algorithm has high estimation precision for the parameters and satisfies the need of building initiating control algorithm for The directional warhead of ATBM missile.

Research on the Vision Processing of Space Robot's Tracking Camera

The tracking camera is very important to the whole test tasks of space robot. Aiming at the vision processing problems of space robots tracking camera, a new method of vision processing LabVIEW+DLL is present in this article. Based on the method, a set of vision processing system of space robots tracking camera is researched and developed. This system can better meet the index requirements of space robots vision processing and precisely measure the position and posture data from the target star relative to space robots body coordinate system in the process of the ground air-float test for the space robot, guaranteeing the smooth completion of the ground test mission.

How to Synchronize and Register an Optical-Inertial Tracking System

Multi-sensor tracking is widely used for augmentation of tracking accuracy using data fusion. A basic requirement for such applications is the real time temporal synchronization and spatial registration of two sensory data. In this study a new method for time and space coordination of two tracking sensor measurements has been presented. For spatial registration we used a body coordinate system and then applied the effect of the level arm. The time synchronization was done based on least mean square (LMS) error method. This method was implemented to synchronize the position and orientation of an object using Inertial ( IMU) and Optical (Optotrak) tracking systems. The results of synchronized data were validated with measurements of Optical tracking system and the mean error of synchronized Euler angles, were less than 0.28 degree.

Research on Spiral Motion of Guided Projectiles Based on Flight Data

To investigate the realistic spiral motion of a spinning guided projectile, a novel analysis method based on flight data is proposed and further applied. A mathematical model of spiral motion is derived in body coordinate system firstly, and the procedures of the novel method are then described in detail. The spiral motion can be induced by non-zero velocity and rotation rate along the longitudinal axis with at least one non-zero velocity and rotation rate along transverse axes. In the case of non-zero velocities and rotation rates exerted along triple axes, it is observed that the spiral motion consists of single circular motion and double circular motion, and the spiral motion depends on both spinning rate and attitude angles of flight trajectory.

Modeling and validation of photometric characteristics of space targets oriented to space-based observation

A modeling and validation method of photometric characteristics of the space target was presented in order to track and identify different satellites effectively. The background radiation characteristics models of the target were built based on blackbody radiation theory. The geometry characteristics of the target were illustrated by the surface equations based on its body coordinate system. The material characteristics of the target surface were described by a bidirectional reflectance distribution function model, which considers the character of surface Gauss statistics and microscale self-shadow and is obtained by measurement and modeling in advance. The contributing surfaces of the target to observation system were determined by coordinate transformation according to the relative position of the space-based target, the background radiation sources, and the observation platform. Then a mathematical model on photometric characteristics of the space target was built by summing reflection components of all the surfaces. Photometric characteristics simulation of the space-based target was achieved according to its given geometrical dimensions, physical parameters, and orbital parameters. Experimental validation was made based on the scale model of the satellite. The calculated results fit well with the measured results, which indicates the modeling method of photometric characteristics of the space target is correct.

Infrared characteristics of on-orbit targets based on space-based optical observation

A modeling method of infrared characteristics of the on-orbit target was presented by a comprehensive consideration of the influence of structure, material, background, attitude and surface self-shadowing of the target at the larger scale. A physical and mathematical model of background radiation was established based on the blackbody radiation theory. The target surface was divided into regions based on structure and material properties and each region was divided into grids by finite element method. Bidirectional Reflection Distribution Function (BRDF) measured in advance was introduced to describe infrared reflection characteristics of each grid and a mathematical model on reflected radiation of the target was built by summing reflection of each grid. The thermal equilibrium temperature of the target surface was calculated by node network method and a mathematical model on emitted radiation of the target was built. Then a body coordinate system was set to describe the relative positions of the target, background radiation sources and detector by coordinate conversion and determine contributed surfaces of the target to the detector. Simulation of the target infrared characteristics on orbit was achieved. The results provide a feasibility of using material properties for satellite detection to within the accuracy of materials measurement and real-time simulation capabilities of computer.

Visible characteristics of space-based targets based on bidirectional reflection distribution function

A precise modeling method of visible characteristics of the space-based target was presented based on bidirectional reflection distribution function (BRDF). The background characteristics of the space-based target were represented to build models of direct solar radiation and reflected radiation of the Earth based on blackbody radiation theory. The geometry characteristics of the target were analyzed to establish a surface equation of each surface based on its body coordinate system. The material characteristics of the target surface were described by introducing a BRDF model which considers the character of surface Gauss statistics and self-shadow and is obtained by measurement and modeling in advance. The relative positions of the space-based target, the background radiation sources and the observation platform were determined based on coordinate conversion to judge contributing surface of the target to observation system. Then a mathematical model on visible characteristics of the space target for the given optical system was built by summing reflection components of all the surfaces. Simulation of visible characteristics of the space-based target in orbit was achieved according to its given geometrical dimensions, physical parameters and orbital parameters. The results show that the method is effective for analysis on visible characteristics of the space-based target when single reflection is considered and its surface is regularly described in a surface equation, which provides a way to real-time calculation of visible characteristics of the space-based target.

Infrared imaging characteristics of space-based targets based on bidirectional reflection distribution function

A modeling method of infrared imaging characteristics of a space-based target was presented. Background radiation environment of a space-based target was analyzed and the background radiation mainly consists of direct radiation of the sun, thermal radiation and reflected radiation of the earth. The target surface was divided into regions based on geometrical shape and surface material characteristics and a surface equation of each region was built based on its body coordinate system. Each region was divided into meshes supposing that each mesh is a micro-plane. A bidirectional reflection distribution function (BRDF) model considering the characteristics of surface Gauss statistics and self-shadow was introduced to describe reflected infrared of each mesh of the target surface. The emitted infrared radiation of each mesh of the target surface was described according to its thermal equilibrium temperature. Then a mathematical model on infrared radiation imaging characteristics of the space-based target was built in terms of the given infrared detector. The relative positions of the space-based target, the background radiation sources and the detector are determined by orbital parameters based on coordinate conversion. Visual surfaces of the target to observation system were determined by vector coordinate method. Simulation of optical imaging characteristics of the target in orbit was achieved according to its given geometrical dimensions and physical parameters. The results show the method is feasible and robust for infrared characteristics of the space-based target when single reflection is considered and its surface is regular and can be described in a surface equation. It can provide a facility to real-time analysis of infrared imaging characteristics of the space-based targets.

Development of a smart oval ball for assessment of angular flight dynamics and precision of kick execution

A smart inflatable oval ball was developed consisting of two simultaneously inflated bladders between which the sensor enclosure was placed, containing three orthogonal MEMS gyroscopes, a data logger and a battery. The smart ball measures the three components of its angular velocity and delivers the following parameters: the spin rate, the precession rate, the spin decay, the position of the spin axis and its elevation angle with respect to the body coordinate system, an index for assessment of kick precision and the wobble angle of the ball with respect to the space coordinate system. The spin-axis vector diagram, colour-coded with progressing time, was displayed on a 3D model of the ball in AutoCAD.

실시간 패턴 변형과 인체 상대좌표계를 이용한 대화형 3D 패턴 디자인

Garment design needs an iterative manipulation of 2D patterns to generate a final sloper. Traditionally there have been two kinds of design methodologies such as the flat pattern method and the pattern draping method. But today, it is possible to combine the advantages from the two methods due to the realistic cloth simulation techniques. We devised a new garment design system which starts from 3D initial drape simulation result and then modifies the garment by editing the 2D flat patterns synchronously. With this interactive methodology using real-time pattern deformation technique, the designer can freely change a pattern shape by watching its 3D outlook in real-time. Also the final garment data were given relative coordinates with respect to the human anthropometric feature points detected by an automatic body feature detection algorithm. Using the relative human body coordinate system, the final garments can be re-used to an arbitrary body data without repositioning in the drape simulation. A female shirt was used for an example and a 3D body scan data was used for an illustration of the feature point detection algorithm.

Bodygraphic Injury Surveillance System

This paper proposes a new technology,``a bodygraphic injury surveillance system (BISS)'' that not only accumulates accident situation data but also represents injury data based on a human body coordinate system in a standardized and multilayered way. Standardized and multilayered representation of injury enables accumulation, retrieval, sharing, statistical analysis, and modeling causalities of injury across different fields such as medicine, engineering, and industry. To confirm the effectiveness of the developed system, the authors collected 3,685 children's injury data in cooperation with a hospital. As new analyses based on the developed BISS, this paper shows bodygraphically statistical analysis and childhood injury modeling using the developed BISS and Bayesian network technology.

Drainage and filling in cylindrical and rectangular containers

Drainage and filling processes in cylindrical and rectangular containers for several motion sequences are experimentally studied using a stereo videogrammetric technique. The measured quantities include the rigid body motion of the containers and the water level relative to the body coordinate system as a function of time. The experimental data are used to validate Torricelli's law and determine the time constant, discharge coefficient, and water volume. In addition, the air funnel shapes in vortical sinks in a stationary cylinder are measured, and the effects of the initial water height and swirling on the drainage are addressed.

The Effects of Femoral Fixed Body Coordinate System Definition on Knee Kinematic Description

Understanding the differences in knee kinematic descriptions is important for comparing data from different laboratories and observing small but important changes within a set of knees. The purpose of this study was to identify how differences in fixed body femoral coordinate systems affect the described tibiofemoral and patellofemoral kinematics for cadaveric knee studies with no hip present. Different methods for describing kinematics were evaluated on a set of seven cadaveric knees during walking in a dynamic knee simulator. Three anatomical landmark coordinate systems, a partial helical axis, and an experimental setup-based system were examined. The results showed that flexion-extension was insensitive to differences in the kinematic systems tested, internal-external rotation was similar for most femoral coordinate systems although there were changes in absolute position, varus-valgus was the most sensitive to variations in flexion axis direction, and anterior-posterior motion was most sensitive to femoral origin location. Femoral coordinate systems that define the sagittal plane using anatomical landmarks and locate the flexion axis perpendicular to the femur's mechanical axis in the frontal plane were typically similar and described kinematics most consistently.

身体地図情報システム

本論文では人間の身体に関係する多様な情報を統合的に管理する身体地図情報システムを提案する．身体地図情報システムは，地理情報システム（GIS）の考え方を応用し，身体座標系と関連づけて，身体に関係する情報を正規化・構造化して記述することで，異分野での情報共有を支援するシステムである．本論文では身体地図情報システムの応用の一つとして，人間の傷害情報を入力・保存・検索・可視化するソフトウェアを実装し，病院で収集した 1,628事例の傷害情報を用いた検証結果を報告する．また，身体地図情報システムによって始めて可能となる傷害情報の統計解析の例として，傷害頻度の可視化や，左右差の統計的検定を行った結果を報告する．

Trajectory Coordinate Constraints in Multibody Railroad Vehicle Systems

In this investigation, the formulation of trajectory coordinate constraints in terms of the absolute coordinates is developed for the use in the computer simulations of railroad vehicle system applications. Examples of trajectory coordinate constraints are the specified forward velocity of a vehicle or a wheelset along a curved track or specified yaw angle of a vehicle or a wheelset with respect to a body trajectory coordinate system. The relationship between the trajectory coordinates and the absolute coordinates is defined and then used to write the trajectory constraints in terms of the absolute coordinates at the position, velocity, and acceleration levels. The motion of the trajectory coordinate system can be uniquely defined in the track body coordinate system using the arc-length coordinate defined along the space curve. It is demonstrated that the use of the trajectory coordinates leads to simple linear constraint equations, while the trajectory constraint equations become highly nonlinear functions of the absolute coordinates. This is mainly due to the nature of the nonlinear relationship between the absolute Cartesian and trajectory coordinates. A numerical example is presented in order to demonstrate the use of the proposed formulations in the analysis of multibody railroad vehicle systems.