Uncertainty Reduction on the Identification of the Inertial Parameters Based on a Complex 3D Motion

2010 ◽  
Author(s):  
Juan P. Barreto M. ◽  
Luis E. Munoz C.
Keyword(s):  
Center Of Mass ◽  
Algebraic Method ◽  
Rigid Bodies ◽  
The Body ◽  
Inertia Tensor ◽  
Identification System ◽  
3D Motion ◽  
Inertial Parameters ◽  
Static Experiment ◽  
Measuring Unit

The uncertainty on the identification of the inertial parameters of rigid bodies can be reduced by studying the motion for the identification experiments. This paper presents a method for measuring the center of mass and the inertia tensor of a rigid body by generating a complex 3D motion. The proposed method is intended to reduce the time consumed by the experiment and the post-processing of the data. This reduction on the time is achieved by using the same assembly for the center of mass and inertia tensor identification experiments as well as an algebraic method for the identification. The experimental setup consists on a Stewart Platform for the generation of the motion, a load cell and an inertial measuring unit. A study on the reduction of the uncertainty was developed. It was found that the uncertainty on the identification of the center of mass can be reduced with a static experiment that takes the object to different orientations, improving the numerical condition of the identification system. The uncertainty on the inertia tensor identification is reduced when the motion of the body is generated relative to different axes in space. The method was first tested on simulations to estimate the uncertainty and then validated experimentally.

scholarly journals Cases of Integrability Which Correspond to the Motion of a Pendulum in the Three-dimensional Space

2021 ◽  
Vol 16 ◽  
pp. 73-84
Author(s):  
Maxim V. Shamolin
Keyword(s):  
Rigid Body ◽  
Force Fields ◽  
Characteristic Point ◽  
Dimensional Space ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Rigid Bodies ◽  
The Body ◽  
Spatial Motion ◽  
Free Rigid Body

We systematize some results on the study of the equations of spatial motion of dynamically symmetric fixed rigid bodies–pendulums located in a nonconservative force fields. The form of these equations is taken from the dynamics of real fixed rigid bodies placed in a homogeneous flow of a medium. In parallel, we study the problem of a spatial motion of a free rigid body also located in a similar force fields. Herewith, this free rigid body is influenced by a nonconservative tracing force; under action of this force, either the magnitude of the velocity of some characteristic point of the body remains constant, which means that the system possesses a nonintegrable servo constraint, or the center of mass of the body moves rectilinearly and uniformly; this means that there exists a nonconservative couple of forces in the system

scholarly journals Método e-zone para cálculos dos parâmetros inerciais de massa corporal

2016 ◽  
Vol 85 (3) ◽  
Author(s):  
Ricardo de Assis Correia ◽  
Wellington Gomes Feitosa ◽  
Lucas Beal ◽  
Luísa Beatriz Trevisan Teixeira ◽  
Cristiano Matos ◽  
...  
Keyword(s):  
Body Mass ◽  
Center Of Mass ◽  
Morphological Characteristics ◽  
Graphical Analysis ◽  
The Body ◽  
Zone Method ◽  
Inertial Parameters ◽  
Calibration Device ◽  
Total Body ◽  
The Right

Introdução: Estimativas corretas dos parâmetros inerciais de massa corporal são de fundamental importância para que análises cinemáticas do centro de massa corporal (CM) sejam mais precisas. Até hoje, as estimativas desses parâmetros inerciais ainda são baseados em protocolos a partir de tabelas gerais para a localização do CM obtidas de estudos em cadáveres. A fim de superar essa limitação, o método de zonas elípticas, e-zone, foi desenvolvido considerando segmentos corporais como zonas elípticas, podendo estimar esses parâmetros, respeitando as individualidades morfológicas corporais, e ser aplicado em diferentes populações.Objetivo: Verificar a sensibilidade de medida do método e-zone em relação à massa corporal total.Introdução: Estimativas corretas dos parâmetros inerciais de massa corporal são de fundamental importância para que análises cinemáticas do centro de massa corporal (CM) sejam mais precisas. Até hoje, as estimativas desses parâmetros inerciais ainda são baseados em protocolos a partir de tabelas gerais para a localização do CM obtidas de estudos em cadáveres. A fim de superar essa limitação, o método de zonas elípticas, e-zone, foi desenvolvido considerando segmentos corporais como zonas elípticas, podendo estimar esses parâmetros, respeitando as individualidades morfológicas corporais, e ser aplicado em diferentes populações.Métodos: Participaram do estudo 13 nadadores federados (21,7 ± 4,2 anos de idade). Foram demarcados círculos (1,5 cm de raio) em 16 acidentes anatômicos corporais. Primeiramente foram registradas as imagens de calibração por meio de fotografias obtidas por 2 câmeras digitais (Olympus HD/3D, 14 megapixels) posicionadas nos planos sagital direito e frontal a 6 m do centro do calibrador. Posteriormente foram registradas as imagens, simultaneamente, por 2 avaliadores posicionados no mesmo local do calibrador. Após esses procedimentos, os dados foram analisados em ambiente MatLab com rotina específica pela qual foram calculados os parâmetros inerciais de cada segmento.Resultados: Entre a massa corporal estimada pelo método e-zone e a massa real dos indivíduos não foi encontrada diferença, o tamanho de efeito foi trivial, houve alta correlação intra-classe e concordância dentro dos limites esperados pela análise gráfica de Bland-Altman.Conclusão: O método e-zone demonstrou ser eficaz em estimar a massa corporal.Method E-Zone to Calculate Inertial Parameters of Body MassIntroduction: Correct estimates of body mass inertial parameters are of fundamental importance for more accurate kinematic analysis of the body center of mass (CM). To date, estimates of these inertial parameters are still based on protocols from general tables to the location of the CM obtained from studies on cadavers. In order to overcome this limitation, the method of elliptic areas e-zone was developed considering body segments as elliptical areas, and can estimate these respecting the body morphological characteristics and applied in different populations.Objective: To determine the sensitivity of the measurement method e-zone relative to total body mass.Methods: This study included 13 federal swimmers (21.7 ± 4.2 years old). They were marked with painted circles (1.5 cm radius) in 16 anatomical accidents around the body. Calibration images were first registered through photographs taken by 2 digital cameras which were positioned in the right sagittal and frontal planes, 6 m from the center of the calibration device. Images of the swimmers were simultaneously obtained by two evaluators in the same location as the calibrator. After these procedures, the data were analyzed in MatLab specific routine in which the inertial parameters of each body segment were calculated.Results: Between the body mass estimated by the e-zone method and the actual mass of individuals there was no difference, the effect size was trivial, there was a high correlation intra class, and there was agreement within the expected limits by graphical analysis of Bland-Altman.Conclusion: The e-zone proved to be effective in estimating body mass.

Reduction of Arbitrary Rigid Bodies to Inertially Equivalent Discrete Systems of Material Points

2015 ◽  
Vol 762 ◽  
pp. 33-40
Author(s):  
Andrei Craifaleanu ◽  
Nicolaie Orăşanu
Keyword(s):  
Center Of Mass ◽  
Discrete Systems ◽  
Rigid Bodies ◽  
The Body ◽  
Plane Plate ◽  
Rigid Plane ◽  
Arbitrary Body ◽  
Material Points ◽  
Cartesian Coordinate ◽  
Mechanical Devices

In a previous paper of the authors, a general method was presented for the reduction of a rigid plane plate to a discrete system of material points, with equivalent inertial properties (mass, center of mass, tensor of inertia). The present paper generalizes the method for rigid bodies of arbitrary shape, i.e. for material volumes, as well as for curved shells. It is shown that a homogenous ellipsoid can be reduced to a system of seven material points placed in significant geometrical points of the body. Next, starting from the concept of ellipsoid of inertia, an equivalent homogenous ellipsoid is determined for an arbitrary body. The method simplifies considerably the calculation of various mechanical quantities, such as moments and products of inertia with respect to rotated Cartesian coordinate systems, angular momentum and kinetic energy, of rigid bodies part of all types of mechanical devices or structures.

scholarly journals A Three-Dimensional Parametric Biomechanical Rider Model for Multibody Applications

2020 ◽  
Vol 10 (13) ◽  
pp. 4509
Author(s):  
Matteo Bova ◽  
Matteo Massaro ◽  
Nicola Petrone
Keyword(s):  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Experimental Comparison ◽  
Minor Effect ◽  
Data Sets ◽  
Data Set ◽  
Multibody Model ◽  
Inertial Parameters ◽  
A Minor

Bicycles and motorcycles are characterized by large rider-to-vehicle mass ratios, thus making estimation of the rider’s inertia especially relevant. The total inertia can be derived from the body segment inertial properties (BSIP) which, in turn, can be obtained from the prediction/regression formulas available in the literature. Therefore, a parametric multibody three-dimensional rider model is devised, where the four most-used BSIP formulas (herein named Dempster, Reynolds-NASA, Zatsiorsky–DeLeva, and McConville–Young–Dumas, after their authors) are implemented. After an experimental comparison, the effects of the main posture parameters (i.e., torso inclination, knee distance, elbow distance, and rider height) are analyzed in three riding conditions (sport, touring, and scooter). It is found that the elbow distance has a minor effect on the location of the center of mass and moments of inertia, while the effect of the knee distance is on the same order magnitude as changing the BSIP data set. Torso inclination and rider height are the most relevant parameters. Tables with the coefficients necessary to populate the three-dimensional rider model with the four data sets considered are given. Typical inertial parameters of the whole rider are also given, as a reference for those not willing to implement the full multibody model.

Improved Measurement Method for the Identification of the Centre of Gravity Location and of the Inertia Tensor of Rigid Bodies

2008 ◽  
Author(s):  
G. Previati ◽  
M. Gobbi ◽  
G. Mastinu
Keyword(s):  
Rigid Bodies ◽  
The Body ◽  
Inertia Tensor ◽  
Testing Time ◽  
Crucial Importance ◽  
Commercial Development ◽  
Centre Of Gravity ◽  
Mass Properties ◽  
Inertia Properties ◽  
Complex Mechanical Systems

The knowledge of the inertia properties of rigid bodies is of crucial importance for the correct simulation of complex mechanical systems. For this purpose at the Politecnico di Milano (Technical university of Milan) a series of test rigs have been constructed for the measurement of mass, centre of gravity location and inertia tensor of rigid bodies with masses ranging from 50 to 3500 kg. The test rigs are basically three or four bar pendulums carrying the body under investigation. The body is made to rotate around three axes passing nearby the body centre of gravity and the resulting highly non linear motion is recorded. A mathematical model simulating the motion of the body carried by the pendulum is used to identify the full inertia tensor by minimising the error between the computed and measured data. These test rigs are currently used for the identification of the mass properties of different cars, light farm tractors, engines, gearboxes and satellites. In this paper a new implementation of these test rigs is shown. By redesigning the instrumentation setup and with a new mathematical procedure for the identification, the test rigs can be used to identify the centre of gravity location and the inertia tensor with a single experimental test. In the new configuration the test rigs require a very short testing time and they are suitable for commercial development.

On the motion of bodies based on changes in the kinetic moment

2019 ◽  
Vol 20 (4) ◽  
pp. 267-275
Author(s):  
Yury N. Razoumny ◽  
Sergei A. Kupreev
Keyword(s):  
Center Of Mass ◽  
Stellar Dynamics ◽  
Elementary Particles ◽  
The Body ◽  
Accelerated Motion ◽  
Indirect Confirmation ◽  
Physical Principles ◽  
Two Bodies ◽  
Central Gravitational Field ◽  
Kinetic Moment

The controlled motion of a body in a central gravitational field without mass flow is considered. The possibility of moving the body in the radial direction from the center of attraction due to changes in the kinetic moment relative to the center of mass of the body is shown. A scheme for moving the body using a system of flywheels located in the same plane in near-circular orbits with different heights is proposed. The use of the spin of elementary particles is considered as flywheels. It is proved that using the spin of elementary particles with a Compton wavelength exceeding the distance to the attracting center is energetically more profitable than using the momentum of these particles to move the body. The calculation of motion using hypothetical particles (gravitons) is presented. A hypothesis has been put forward about the radiation of bodies during accelerated motion, which finds indirect confirmation in stellar dynamics and in an experiment with the fall of two bodies in a vacuum. The results can be used in experiments to search for elementary particles with low energy, explain cosmic phenomena and to develop transport objects on new physical principles.

scholarly journals Effect of foot–floor friction on the external moment about the body center of mass during shuffling gait: a pilot study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takeshi Yamaguchi ◽  
Kei Shibata ◽  
Hiromi Wada ◽  
Hiroshi Kakehi ◽  
Kazuo Hokkirigawa
Keyword(s):  
Friction Surface ◽  
Center Of Mass ◽  
Young Male ◽  
The Body ◽  
Low Friction ◽  
Surface Conditions ◽  
Normal Gait ◽  
External Moment ◽  
Body Center ◽  
Floor Condition

AbstractHerein, we investigated the effect of friction between foot sole and floor on the external forward moment about the body center of mass (COM) in normal and shuffling gaits. Five young male adults walked with normal and shuffling gaits, under low- and high-friction surface conditions. The maximum external forward moment about the COM (MEFM-COM) in a normal gait appeared approximately at initial foot contact and was unaffected by floor condition. However, MEFM-COM in a shuffling gait under high-friction conditions exceeded that under low-friction conditions (p < 0.001). Therein, MEFM-COM increased with an increasing utilized coefficient of friction at initial foot contact; this effect was weaker during a normal gait. These findings indicate that increased friction between foot sole and floor might increase tripping risk during a shuffling gait, even in the absence of discrete physical obstacles.

Development of the Meridian-Visualizing System that Superimposes a Bio-signal upon a Body Image

2004 ◽  
Vol 32 (04) ◽  
pp. 631-640
Author(s):  
Dong-Myong Jeong ◽  
Yong-Heum Lee ◽  
Myeong Soo Lee
Keyword(s):  
Body Image ◽  
Skin Resistance ◽  
The Body ◽  
Acupuncture Points ◽  
Identification System ◽  
Electrode Position ◽  
Excitation Current ◽  
System A ◽  
Dc Excitation ◽  
Single Power

The precise selection and the identification of acupuncture points are essential for the diagnosis and treatment of patients in Oriental medicine. In this study, we have developed a meridian identification system using Single-Power Alternating Current (SPAC), which discriminates between true acupoints and non-acupoints. The SPAC system is not affected by skin resistance or pressure and is more accurate than the existing meridian location system, which uses direct current (DC) excitation current. The accuracy of the meridian location is ensured with the SPAC system because it has the highest sensitivity and the lowest effect on the human body. A microprocessor is used to enhance reliability and increase the accuracy of the SPAC measurements. Current distribution is displayed using an image that overlays the measured skin current on the body image. The positions of the acupoints are then displayed on the body image. This method visualizes the meridian by measuring skin current with an improved electrode using the acupoint discrimination system. A computer display shows the transmitted current as a color related to the electrode position. We demonstrated that by changing the point of measurement on the skin and tracing the electrode on the screen, it is possible to visualize acupoints and meridian phenomena using the color display.

scholarly journals Can Muscle Stiffness Alone Stabilize Upright Standing?

1999 ◽  
Vol 82 (3) ◽  
pp. 1622-1626 ◽  
Author(s):  
Pietro G. Morasso ◽  
Marco Schieppati
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Muscle Stiffness ◽  
The Body ◽  
Ankle Muscles ◽  
Upright Standing ◽  
Stiffness Control ◽  
Control Patterns ◽  
Physiological Values

A stiffness control model for the stabilization of sway has been proposed recently. This paper discusses two inadequacies of the model: modeling and empiric consistency. First, we show that the in-phase relation between the trajectories of the center of pressure and the center of mass is determined by physics, not by control patterns. Second, we show that physiological values of stiffness of the ankle muscles are insufficient to stabilize the body “inverted pendulum.” The evidence of active mechanisms of sway stabilization is reviewed, pointing out the potentially crucial role of foot skin and muscle receptors.

3D Motion of Rigid Bodies

2019 ◽  
Author(s):  
Ernesto Olguín Díaz
Keyword(s):  
Rigid Bodies ◽  
3D Motion
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