Determining the Static Joint Torques of a Digital Human Model Considering Balance

2009 ◽  
Author(s):  
Jingzhou James Yang ◽  
Yujiang Xiang ◽  
Joo Kim
Keyword(s):  
Human Model ◽  
Joint Torques ◽  
Digital Human Model ◽  
Human Models ◽  
Support Reaction ◽  
Reaction Forces ◽  
Zero Moment ◽  
The Stability ◽  
Physics Based Simulation ◽  
Digital Human

This paper presents a methodology for determining the static joint torques of a digital human model considering balance for both standing and seating tasks. An alternative and efficient formulation of the Zero-Moment Point (ZMP) for static balance and the approximated (ground/seat) support reaction forces/moments are derived from the resultant reaction loads, which includes the gravity and externally applied loads. The proposed method can be used for both standing and seating tasks for assessing the stability/balance of the posture. The proposed formulation can be beneficial to physics-based simulation of humanoids and human models. Also, the calculated joint torques can be considered as an indicator to assess the risks of injuries when human models perform various tasks.

Static Joint Torque Determination of a Human Model for Standing and Seating Tasks Considering Balance

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
Jingzhou (James) Yang ◽  
Joo H. Kim
Keyword(s):  
Material Handling ◽  
Weight Lifting ◽  
Joint Torque ◽  
Human Model ◽  
Computational Time ◽  
Joint Torques ◽  
Human Models ◽  
Support Reaction ◽  
The Stability ◽  
Physics Based Simulation

Estimation of the risk of injury to human different joints during occupational tasks plays an important role to reduce injuries before the operators carry out the tasks. This paper presents a methodology for determining the static joint torques of a human model considering balance for both standing and seating tasks such as weight lifting, material handling, and seated operating tasks in the assembly line. A high fidelity human model has been developed, and recursive dynamics has been used to formulate the static equation of motion. An alternative and efficient formulation of the zero-moment point for static balance and the approximated (ground/seat) support reaction forces/moments are derived from the resultant reaction loads, which includes the gravity and externally applied loads. The proposed method can be used for both standing and seating tasks for assessing the stability/balance of the posture. The proposed formulation can be beneficial to physics-based simulation of humanoids and human models. Also, the calculated joint torques can be considered as an indicator to assess the risks of injuries when human models perform various tasks. The computational time for each case is close to 0.015 s.

Human Carrying Simulation With Symmetric and Asymmetric Loads

2012 ◽  
Author(s):  
Yujiang Xiang ◽  
Jasbir S. Arora ◽  
Salam Rahmatalla ◽  
Hyun-Joon Chung ◽  
Rajan Bhatt ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Human Motion ◽  
Human Model ◽  
Physical Constraints ◽  
Digital Human Model ◽  
Load Carrying ◽  
Reaction Forces ◽  
Asymmetric Load ◽  
Optimization Schemes ◽  
Digital Human

Human carrying is simulated in this work by using a skeletal digital human model with 55 degrees of freedom (DOFs). Predictive dynamics approach is used to predict the carrying motion with symmetric and asymmetric loads. In this process, the model predicts joints dynamics using optimization schemes and task-based physical constraints. The results indicated that the model can realistically match human motion and ground reaction forces data during symmetric and asymmetric load carrying task. With such prediction capability the model could be used for biomedical and ergonomic studies.

Optimization-Based Prediction of Aiming and Kneeling Military Tasks Performed by a Soldier

2012 ◽  
Author(s):  
Mahdiar Hariri ◽  
Jasbir Arora ◽  
Karim Abdel-Malek
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Problem ◽  
Human Model ◽  
Ground Reaction Forces ◽  
Optimization Approach ◽  
Ground Contact ◽  
Digital Human Model ◽  
Reaction Forces ◽  
Digital Human ◽  
The Given

The objective of this study is to predict the “Aiming While Standing” and “Aiming While Kneeling” motion tasks for a soldier (human) using a full-body, three dimensional digital human model. The digital human is modeled as a 55 degree of freedom branched mechanism. Six degrees of freedom specify the global position and orientation of the coordinate frame attached to the pelvis of the digital human and 49 degrees of freedom represent the revolute joints which model the human joints and determine the kinematics of the entire digital human. Motion is generated by a multi-objective optimization approach minimizing the mechanical energy and joint discomfort simultaneously. A sequential quadratic programming (SQP) algorithm in SNOPT is used to solve the nonlinear optimization problem. The optimization problem is subject to constraints which represent the limitations of the environment, the digital human model and the motion task. Design variables are the joint angle profiles. All the forces, inertial, gravitational as well as external, are known, except the ground reaction forces. The feasibility of the generation of that arbitrary motion by using the given ground contact areas is ensured by using the well known Zero Moment Point (ZMP) constraint. During the kneeling motion, different parts of the body come in contact and lose contact with the ground which is modeled using a general approach. The ground reaction force on each transient ground contact area is determined using the equations of motion. It is assumed that enough friction exists that allow the human to generate reaction forces as determined by the ZMP constraint. Using these ground reaction forces, the required torques at all joints are calculated by the recursive Lagrangian formulation. Using the given method, we can predict realistic motions for the “Aiming While Standing” and “Aiming While Kneeling” tasks. The optimization approach is able to very well predict the “Natural Point of Aim” which is a well known concept for soldiers. In other words, the approach is able to predict the most comfortable final orientation of the feet on the ground for engaging a specific target. We also predict cases where the orientation of the soldier’s feet are enforced. Many virtual experiments have been conducted by changing the target location in the 3D space, changing the anthropometry of the soldier, adding armor to different joints, changing the variable parameters of the rifle, adding backpack and using different weapons.

Optimization-Based Seated Posture Prediction Considering Contact With Environment

2011 ◽  
Author(s):  
Brad Howard ◽  
Jingzhou James Yang
Keyword(s):  
Center Of Pressure ◽  
Optimization Techniques ◽  
The Body ◽  
Human Model ◽  
Joint Torques ◽  
Pressure Mapping ◽  
Support Reaction ◽  
Posture Prediction ◽  
Reaction Forces ◽  
Recursive Dynamics

People can spend much of everyday completing seated tasks. Therefore it is important to understand postures needed to complete seated tasks, and the associated environmental contacts. This paper presents a method to predict seated postures and the general forces needed in order to support resulting postural configurations. This study uses optimization techniques to predict human posture based on a 56 degree of freedom (DOF) 50th percentile female human model. The support reaction forces (SRFs) are predicted using joint torques and the zero-moment point (ZMP) formulation derived from the Lagrangian recursive dynamics. The SRFs are applied at points on the body based on center of pressure (COP) locations gathered from pressure mapping experiments. The specific application points include the two feet, the two thighs, and back. Multiple seated orientations based on an experimental study found in published literature are simulated. When comparing these simulation results to the literature data, a good correlation can be established, which provides an initial validation of the proposed methods.

A NEW STABILITY CRITERION FOR HUMAN SEATED TASKS WITH GIVEN POSTURES

2012 ◽  
Vol 09 (03) ◽  
pp. 1250015 ◽  
Author(s):  
BRADLEY HOWARD ◽  
JINGZHOU YANG
Keyword(s):  
Stability Analysis ◽  
Stability Criterion ◽  
Center Of Mass ◽  
Reaction Force ◽  
Joint Torque ◽  
Human Model ◽  
Digital Human Model ◽  
Applied Forces ◽  
The Stability ◽  
Digital Human

In digital human modeling (DHM), the analysis of postural stability has five main goals: to determine if a posture is stable or unstable through an explicit criterion; to quantify the level of stability or provide a margin of stability that accounts for the height of the center of mass (COM) above the support plane(s); to be valid in the presence of externally applied forces and moments; be able to assess stability when multiple noncoplanar support planes exist, as is the case with seated postures; and to give insight into the support reaction force (SRF) distribution. To date, there is not a method for analyzing stability that can effectively meet each goal. This paper presents a new stability criterion and stability analysis that accomplishes each intended goal. The stability analysis is derived from the calculation of joint torque using the recursive Lagrangian dynamic formulation. A 56-degree-of-freedom (DOF) articulated digital human model is used to model seated postures to demonstrate the proposed stability criterion. Different given postures with different external load cases are presented.

Human Stair Ascent and Descent Simulations

2014 ◽  
Author(s):  
Yujiang Xiang ◽  
Joo H. Kim ◽  
Hyun-Joon Chung ◽  
James Yang ◽  
Hyun-Jung Kwon
Keyword(s):  
Degrees Of Freedom ◽  
Human Motion ◽  
Stair Climbing ◽  
Human Model ◽  
Physical Constraints ◽  
Digital Human Model ◽  
Stair Ascent ◽  
Reaction Forces ◽  
Optimization Schemes ◽  
Digital Human

Human stair ascent and descent are simulated in this work by using a skeletal digital human model with 55 degrees of freedom (DOFs). Hybrid predictive dynamics approach is used to predict the stair climbing motion with weapons and backpacks. In this process, the model predicts joints dynamics using optimization schemes and task-based physical constraints. The results indicated that the model can realistically match human motion and ground reaction forces data during stair climbing tasks. This can be used in human health domain such as leg prosthesis design.

Industrial Design of Motorcycle with Reference to Indian Population

2014 ◽  
Vol 592-594 ◽  
pp. 2659-2664 ◽  
Author(s):  
T. Jeyakumar ◽  
R. Gandhinathan
Keyword(s):  
Optimal Solution ◽  
Human Model ◽  
Anthropometric Data ◽  
Posture Analysis ◽  
Digital Human Model ◽  
Set Up ◽  
The Aesthetic ◽  
Decision Making Model ◽  
Digital Human ◽  
Data Collection Approach

India is the second largest 2W market in the world in terms of sales volumes after China. Motorcycles types that are marketed using sports tag are found to be anchored on performance attributes characterized by visual appeal, higher speeds, heady acceleration and superior ride, handling and braking. The chronograph of the sports segment in the Indian market is plotted. A goal defined design process is developed to produce creative ideas for aesthetic attributes-modern, youthful, aerodynamic, and aggressive. The optimal solution satisfying the aesthetic goal is determined using an operation decision making model based upon weighted generalized mean method. A motorcycle is generally straddled by the rider with manual transmission and can be considered as a constrained workstation. Some ergonomic considerations to fit users of different sizes on the same workstation should be taken into account when designing. A two-dimensional anthropometric data collection approach is followed for riders in India. The obtained anthropometric data concerning riding postures are used for posture analysis using digital human model in CAD software. The mutual trade-off between sporty riding style of the rider and comfort angles have been arrived to set up the final posture of the rider. The detailing of the appearance considering the aesthetic attributes and ergonomics are done. The developed design is aimed at improving appearance and ergonomic performance.

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