A Momentum-Based Algorithm for Identifying the Inertia Properties of a Human Body: A Preliminary Study

2010 ◽  
Author(s):  
Qi Lu ◽  
Ou Ma
Keyword(s):  
Human Body ◽  
Measurement Errors ◽  
Equations Of Motion ◽  
Least Square Method ◽  
Internal Force ◽  
Momentum Equation ◽  
The Body ◽  
Least Square ◽  
Identification Algorithm ◽  
Force Data

The body segment parameters (BSP) of a human body are critical information for modeling, simulating, and understanding human dynamics. The determination of BSPs of human bodies has received increasing attention in biomechanics, sport science, ergonomics, rehabilitation and other fields. This paper presents a momentum-based identification algorithm for dynamically estimating the BSPs of a human body. The human body is modeled as a multibody dynamical system, and the momentum equation of the system can be derived by applying the principle of impulse and momentum. It is possible to formulate the momentum equations corresponding to a set of experiment tests into a linear regression form with respect to the unknown BSPs, which then can be solved using the least square method or other methods. The momentum-based algorithm requires inputting position, velocity, and external force data only. Since acceleration and all the internal force data is not needed, the algorithm is less demanding on measurements and is also less sensitive to measurement errors. As a result, it is practically more appealing than the algorithms depending on the equations of motion. The paper presents the momentum-based inertia identification algorithm along with a simulation study of the algorithm using a simplified trunk-leg model representing a main portion of a human body.

Identification of Human Inertia Properties Using a Momentum-Based Approach

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Qi Lu ◽  
Ou Ma
Keyword(s):  
Human Body ◽  
Measurement Errors ◽  
Least Square Method ◽  
Least Square ◽  
Identification Procedure ◽  
Lagrangian Equations ◽  
Internal Forces ◽  
Inertia Properties ◽  
Dynamics Simulations ◽  
Tree Type

This paper presents a momentum-based approach for identifying the barycentric parameters of a human body. The human body is modeled as a multiple rigid-body dynamical system with a tree-type topology using the principle of impulse and momentum. Since the resulting impulse-momentum equations are linear in terms of the unknown barycentric parameters, these parameters can be easily solved using the least-square method or other well-understood solution techniques. The approach does not require measuring or estimating accelerations and internal forces because they do not appear in the impulse-momentum equations and, thus, the resulting identification procedure is less demanding on the measurement and also less sensitive to measurement errors in comparison with other existing methods derived based on Newton-Euler or Lagrangian equations. The momentum-based approach has been studied by dynamics simulations with the consideration of possible measurement errors. The study showed good results.

Modeling of Human Reactions to Whole-Body Vibration

1987 ◽  
Vol 109 (3) ◽  
pp. 210-217 ◽  
Author(s):  
Farid M. L. Amirouche
Keyword(s):  
Human Body ◽  
Equations Of Motion ◽  
Vertical Direction ◽  
The Body ◽  
Whole Body ◽  
Connective Tissues ◽  
Finite Segment ◽  
Body Vibration ◽  
Forcing Function ◽  
Impulse Function

A computer-automated approach for studying the human body vibration is presented. This includes vertical, horizontal, and torsional vibration. The procedure used is based on Finite Segment Modeling (FSM) of the human body, thus treating it as a mechanical structure. Kane’s equations as developed by Huston et al. are used to formulate the governing equations of motion. The connective tissues are modeled by springs and dampers. In addition, the paper presents the transient response of different parts of the body due to a sinusoidal forcing function as well as an impulse function applied to the lower torso in the vertical direction.

scholarly journals The Role of the Location of Personal Exposimeters on the Human Body in Their Use for Assessing Exposure to the Electromagnetic Field in the Radiofrequency Range 98–2450 MHz and Compliance Analysis: Evaluation by Virtual Measurements

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Krzysztof Gryz ◽  
Patryk Zradziński ◽  
Jolanta Karpowicz
Keyword(s):  
Human Body ◽  
Measurement Errors ◽  
The Body ◽  
Back Side ◽  
Human Body Model ◽  
Field Exposure ◽  
Limit Values ◽  
Exposure Limit ◽  
Measurement Results ◽  
Exposure Conditions

The use of radiofrequency (98–2450 MHz range) personal exposimeters to measure the electric field (E-field) in far-field exposure conditions was modelled numerically using human body model Gustav and finite integration technique software. Calculations with 256 models of exposure scenarios show that the human body has a significant influence on the results of measurements using a single body-worn exposimeter in various locations near the body ((from −96 to +133)%, measurement errors with respect to the unperturbedE-field value). When an exposure assessment involves the exposure limitations provided for the strength of an unperturbedE-field. To improve the application of exposimeters in compliance tests, such discrepancies in the results of measurements by a body-worn exposimeter may be compensated by using of a correction factor applied to the measurement results or alternatively to the exposure limit values. The location of a single exposimeter on the waist to the back side of the human body or on the front of the chest reduces the range of exposure assessments uncertainty (covering various exposure conditions). However, still the uncertainty of exposure assessments using a single exposimeter remains significantly higher than the assessment of the unperturbedE-field using spot measurements.

Optimal Weighted Least Square Data Fusion Method for Redundant IMU Based on Calculation of Measurement Error

2012 ◽  
Vol 241-244 ◽  
pp. 149-155
Author(s):  
Chuan Xing ◽  
Hai Zhang
Keyword(s):  
Measurement Error ◽  
Data Fusion ◽  
Measurement Errors ◽  
Least Square Method ◽  
Least Square ◽  
Weighted Least Square ◽  
Weighted Matrix ◽  
Measurement Results ◽  
The Difference ◽  
Projection Error

A dodecahedron non-orthogonal redundant IMU configuration was selected as model. To improve fusion accuracy, we proposed an effective calculation method for measurement errors based on the correlation between measurement errors and fusion errors. The method considered the difference between traditional data fusion vector’s projection and measurement results, and then made a conversion from projection error to measurement error. Combined with optimal weighted least square method, measurement error was used to generate an optimal weighted matrix, and this made data fusion errors minimum. Simulations also proved that the fusion result of this method is more accurate than the result of traditional method.

Real-Time Direct Position Analysis of Parallel Spherical Wrists by Using Extra Sensor Data

2004 ◽  
Author(s):  
R. Vertechy ◽  
V. Parenti-Castelli
Keyword(s):  
Real Time ◽  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Point Of View ◽  
The Body ◽  
Least Square ◽  
Sensor Data ◽  
End Effector ◽  
Kinematic Chains ◽  
Position Analysis

The paper presents an algorithm for the real-time evaluation of the actual end-effector orientation (pose) of general parallel spherical wrists. Conceptually, the method relies on the evidence that the pose of a rigid body is defined once the location of at least two linearly independent vectors attached to the body is known. The location of these vectors of the wrist end-effector is determined by the solution of the direct position analysis of some properly chosen kinematic chains (legs) of the manipulator. In order to accomplish this analysis, extra-sensors, which measure suitable non-actuated variables of the chosen legs, need to be placed in addition to the ones normally embedded in the servo motors, i.e. the sensors which measure the actuated variables. From a mathematical point of view, the algorithm is built on the Polar Decomposition of a matrix and has inherent least square features. Thus, together with measurement redundancy, i.e. more sensors (extra-sensors) than the mechanism degrees of freedom, the method also allows minimizing the influence of both round-off and measurement errors on the estimation of the location of the wrist end-effector. The method is general but, in order to prove its effectiveness, without loss of generality it has been customized to the solution of the (3-UPS)S fully parallel wrist architecture. Comparison of the proposed method, in both its general and specialized form, with others from the literature is provided.

An Application of Least Squares Method to the Solution of the Inverse Problem of Heat Conduction

1963 ◽  
Vol 85 (4) ◽  
pp. 378-379 ◽  
Author(s):  
Irving Frank
Keyword(s):  
Experimental Data ◽  
Inverse Problem ◽  
Heat Conduction ◽  
Least Squares ◽  
Heat Input ◽  
Least Squares Method ◽  
Least Square Method ◽  
The Body ◽  
Least Square

When the temperature of a body at some point is known, it is generally possible to determine the rate of heat input to the surface of the body. However, when the temperatures are determined experimentally, it will be found that there is some uncertainty in the solution for the rate of heat input. It is suggested that a least square method be used to determine the rate of heat input which best fits the experimental data.

Mechanical Parameters of Standing Body and Applications in Human–Structure Interaction

2017 ◽  
Vol 09 (02) ◽  
pp. 1750021 ◽  
Author(s):  
Huixuan Han ◽  
Ding Zhou ◽  
Tianjian Ji
Keyword(s):  
Dynamic Characteristics ◽  
Human Body ◽  
Damping Ratio ◽  
Coupled System ◽  
The Body ◽  
Degree Of Freedom ◽  
Least Square ◽  
Mechanical Parameters ◽  
Structure Interaction ◽  
Body Model

In this paper, the dynamic interaction of human body and structure is studied The shaking table experiment with a person standing on a rigid table supported by springs is firstly carried out to determine the dynamic characteristics of the coupled system. It is shown that the body mainly contributes only one degree of freedom to the human-structure coupled system. Then, the two-degree-of-freedom (TDOF) coupled model of the human-structure system is developed through the energy variation by considering the standing human body as an elastic bar of two segments with distributed mass, stiffness and damping. Based on the experiment data, the dynamic parameters of the TDOF coupled system are determined by using the least square method (LSM). The mechanical parameters such as the damping ratio and the distributions of mass and stiffness of the human body model of two segments are identified by adopting the inversing technique Finally, the determined body model is applied to analyze the free vibration of beams and plates occupied by standing persons. The governing differential equations of the human-beam system and the human-plate system are, respectively, derived out. The dynamic characteristics of the human-structure interaction are obtained by the use of the complex mode theory. The results are compared with the experimental ones and those from the finite element simulations. Good agreement is observed for all cases.

Identification and Defect Detection of Continuous Dynamic Systems

2006 ◽  
Author(s):  
A. Siami ◽  
M. Farid
Keyword(s):  
Finite Difference ◽  
Differential Equations ◽  
Defect Detection ◽  
Equations Of Motion ◽  
Continuous System ◽  
Least Square Method ◽  
Least Square ◽  
Continuous Systems ◽  
Algebraic Equations ◽  
Continuous Dynamic

This paper presents a systematic and efficient algorithm using a coupled finite element - finite difference - least square method for identification and defect detection of continuous system using dynamic response of such systems. First the governing partial differential equations of motion of continuous systems such as beams are reduced to a set of ordinary differential equations in time domain using finite elements. Then finite difference method is used to convert these equations into a set of algebraic equations. This set of equations is considered as a set of equality constraints of an optimization problem in which the objective function is the summation of the squares of differences between measured data at specific points and the predicted data obtained by the solution of the governing system of differential of equations. This method has been successfully applied to find mechanical properties of aforementioned systems in an iterative procedure.

scholarly journals Boundary-layer separation in circular diffuser flows in the presence of an external non-uniform magnetic field

2020 ◽  
Vol 11 (1) ◽  
pp. 39-48
Author(s):  
Seyed Morteza Moghimi ◽  
Morteza Abbasi ◽  
Mehran Khaki Jamei ◽  
Davood Domiri Ganji
Keyword(s):  
Magnetic Field ◽  
Numerical Method ◽  
Field Intensity ◽  
Magnetic Field Intensity ◽  
Least Square Method ◽  
Boundary Layer Separation ◽  
Nonlinear Ordinary Differential Equation ◽  
Momentum Equation ◽  
Least Square ◽  
The Magnetic Field

Abstract. The focus of the present work is on the investigation of the separation point and its relative location in a circular diffuser carrying incompressible laminar flow in the presence of a non-uniform external magnetic field. Two different approaches are deployed in the present analysis. In the first approach, a similarity transform is applied to reduce the momentum equation to the nonlinear ordinary differential equation (ODE). The ODE is solved by a dual integral–numerical method and the separation position is directly determined. In this combined numerical–integral methodology, the integration is applied followed by a numerical method. In the second approach, the equation is solved by the least square method (LSM), and the separation position is indirectly specified. In this study it is shown that the magnetic field intensity can be manipulated to postpone the separation such that it could be eliminated totally. Comparing the results yields a good agreement. It has been concluded that by increasing the magnetic field intensity, as the Lorentz force increases, increased shear stress on the wall and delay in the occurrence of the separation position are observed.

scholarly journals Payload Identification and Gravity/Inertial Compensation for Six-Dimensional Force/Torque Sensor with a Fast and Robust Trajectory Design Approach

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 439
Author(s):  
Jinjun Duan ◽  
Zhouchi Liu ◽  
Yiming Bin ◽  
Kunkun Cui ◽  
Zhendong Dai
Keyword(s):  
Force Control ◽  
Inertial Force ◽  
Least Square Method ◽  
Force Sensor ◽  
Rapid Identification ◽  
Least Square ◽  
Trajectory Design ◽  
Identification Algorithm ◽  
Torque Sensor ◽  
Compensation Algorithm

In the robot contact operation, the robot relies on the multi-dimensional force/torque sensor installed at the end to sense the external contact force. When the effective load and speed of the robot are large, the gravity/inertial force generated by it will have a non-negligible impact on the output of the force sensor, which will seriously affect the accuracy and effect of the force control. The existing identification algorithm time is often longer, which also affects the efficiency of force control operations. In this paper, a self-developed multi-dimensional force sensor with integrated gravity/inertial force sensing function is used to directly measure the resultant force. Further, a method for the rapid identification of payload based on excitation trajectory is proposed. Firstly, both a gravity compensation algorithm and an inertial force compensation algorithm are introduced. Secondly, the optimal spatial recognition pose based on the excitation trajectory was designed, and the excitation trajectory of each joint is represented by a finite Fourier series. The least square method is used to calculate the identification parameters of the load, the gravity, and inertial force. Finally, the experiment was verified on the robot. The experimental results show that the algorithm can quickly identify the payload, and it is faster and more accurate than other algorithms.

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