Predictive Simulation of Human Walk-to-Run Transition

2012 ◽  
Author(s):  
Hyun-Joon Chung ◽  
Yujiang Xiang ◽  
Rajan Bhatt ◽  
Jasbir S. Arora ◽  
Karim Abdel-Malek
Keyword(s):  
Optimal Solution ◽  
Joint Torques ◽  
Double Support ◽  
Physical Constraints ◽  
Transition Prediction ◽  
Optimization Formulation ◽  
Reaction Forces ◽  
Step Transition ◽  
Skeletal Model ◽  
Dynamics Method

A general optimization formulation for walk-to-run transition prediction using 3D skeletal model is presented. The walk-to-run transition is used to connect fast walking to slow running by using a step-to-step transition formulation. Walk-to-run transition includes four phases: double support walking phase, single support swinging phase, running phase, and finally single support running phase. The transition task is formulated as an optimization problem in which the dynamic effort is minimized subject to basic physical constraints. The joint torques and ground reaction forces (GRF) are recovered and analyzed from the simulation. The optimal solution of transition simulation is obtained in a few minutes by using predictive dynamics method.

Muscle Force Prediction of 2D Gait Using Predictive Dynamics Optimization

2016 ◽  
Author(s):  
Yujiang Xiang
Keyword(s):  
Degrees Of Freedom ◽  
Muscle Force ◽  
Optimal Solution ◽  
Human Motion ◽  
Human Gait ◽  
Predictive Dynamics ◽  
Physical Constraints ◽  
Reaction Forces ◽  
Muscle Groups ◽  
Optimization Schemes

Cyclic human gait is simulated in this work by using a 2D musculoskeletal model with 12 degrees of freedom (DOF). Eight muscle groups are modeled on each leg. Predictive dynamics approach is used to predict the walking motion. In this process, the model predicts joints dynamics and muscle forces simultaneously using optimization schemes and task-based physical constraints. The results indicated that the model can realistically match human motion, ground reaction forces (GRF), and muscle force data during walking task. The proposed optimization algorithm is robust and the optimal solution is obtained in seconds. This can be used in human health domain such as leg prosthesis design.

Physics-Based Seated Posture Prediction for Pregnant Women and Validation Considering Ground and Seat Pan Contacts

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Bradley Howard ◽  
Aimee Cloutier ◽  
Jingzhou (James) Yang
Keyword(s):  
Pregnant Women ◽  
Objective Function ◽  
Linear Regression Analysis ◽  
Joint Torque ◽  
Joint Torques ◽  
Design Variables ◽  
Optimization Formulation ◽  
Posture Prediction ◽  
Seated Posture ◽  
End Effectors

An understanding of human seated posture is important across many fields of scientific research. Certain demographics, such as pregnant women, have special postural limitations that need to be considered. Physics-based posture prediction is a tool in which seated postures can be quickly and thoroughly analyzed, as long the predicted postures are realistic. This paper proposes and validates an optimization formulation to predict seated posture for pregnant women considering ground and seat pan contacts. For the optimization formulation, the design variables are joint angles (posture); the cost function is dependent on joint torques. Constraints include joint limits, joint torque limits, the distances from the end-effectors to target points, and self-collision avoidance constraints. Three different joint torque cost functions have been investigated to account for the special postural characteristics of pregnant women and consider the support reaction forces (SRFs) associated with seated posture. Postures are predicted for three different reaching tasks in common reaching directions using each of the objective function formulations. The predicted postures are validated against experimental postures obtained using motion capture. A linear regression analysis was used to evaluate the validity of the predicted postures and was the criteria for comparison between the different objective functions. A 56 degree of freedom model was used for the posture prediction. Use of the objective function minimizing the maximum normalized joint torque provided an R2 value of 0.828, proving superior to either of two alternative functions.

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.

scholarly journals Simulation of Stand-to-Sit Biomechanics for Design of Lower-Limb Exoskeletons and Prostheses with Energy Regeneration

2019 ◽  
Author(s):  
Brock Laschowski ◽  
Reza Sharif Razavian ◽  
John McPhee
Keyword(s):  
Lower Limb ◽  
Electrical Energy ◽  
Mechanical Power ◽  
Future Research ◽  
Ground Reaction Forces ◽  
Dynamic Simulations ◽  
Inverse Dynamic ◽  
Joint Torques ◽  
Reaction Forces ◽  
Body Segment Parameters

AbstractAlthough regenerative actuators can extend the operating durations of robotic lower-limb exoskeletons and prostheses, these energy-efficient powertrains have been exclusively designed and evaluated for continuous level-ground walking.ObjectiveHere we analyzed the lower-limb joint mechanical power during stand-to-sit movements using inverse dynamic simulations to estimate the biomechanical energy available for electrical regeneration.MethodsNine subjects performed 20 sitting and standing movements while lower-limb kinematics and ground reaction forces were measured. Subject-specific body segment parameters were estimated using parameter identification, whereby differences in ground reaction forces and moments between the experimental measurements and inverse dynamic simulations were minimized. Joint mechanical power was calculated from net joint torques and rotational velocities and numerically integrated over time to determine joint biomechanical energy.ResultsThe hip produced the largest peak negative mechanical power (1.8 ± 0.5 W/kg), followed by the knee (0.8 ± 0.3 W/kg) and ankle (0.2 ± 0.1 W/kg). Negative mechanical work from the hip, knee, and ankle joints per stand-to-sit movement were 0.35 ± 0.06 J/kg, 0.15 ± 0.08 J/kg, and 0.02 ± 0.01 J/kg, respectively.Conclusion and SignificanceAssuming an 80-kg person and previously published regenerative actuator efficiencies (i.e., maximum 63%), robotic lower-limb exoskeletons and prostheses could theoretically regenerate ~26 Joules of total electrical energy while sitting down, compared to ~19 Joules per walking stride. Given that these regeneration performance calculations are based on healthy young adults, future research should include seniors and/or rehabilitation patients to better estimate the biomechanical energy available for electrical regeneration among individuals with mobility impairments.

Decision-making approach for complex problems management in a scarce human resources environment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marcilio Andrade ◽  
Dermeval Carinhana Jr
Keyword(s):  
Decision Making ◽  
Human Resources ◽  
Theoretical Perspective ◽  
Optimal Solution ◽  
Complex Problem ◽  
Theory Of Constraints ◽  
Content Type ◽  
Physical Constraints ◽  
Complex Problems ◽  
The Relationship

Purpose This purpose of this study is to structure complex problems to be solved with greater efficiency, optimising the relationship between root causes (RC) relevance of the problem and utilisation of human resources to treat them, minimising the use of manpower in problem-solving activity and thus contributing to greater productivity within organisations. Design/methodology/approach The authors built an approach under the concepts of theory of constraints and multiattribute and multiobjective decision-making methods that were applied in a real complex problem of the low development of Brazilian space industry, by theoretical perspective. Also, the authors submitted it in a simulation environment to assess in which situations it is successful considering number of problem’s RC, system complexity and number of people in the system. Findings The approach was successful on the real case, finding the optimal relationship between the RC relevance and the number of people involved to treat them. For certain complex problem inputs configurations, simulation results reveal that the approach is reliable obtaining more than 95% chance of success in finding the optimal relationship, when comparing with traditional prioritising methods. Originality/value This approach introduces an unprecedented way to locate and evaluate non-physical constraints within a system, which is used to determine RC relevance, as well as an unprecedented way of defining a single optimal solution for structuring a problem, considering the relevance of RC and the use of human resources. The approach is useful for organisations in general which often need managing complex problems with few resources.

New Hybrid Discrete PSO for Solving Non Convex Trim Loss Problem

2012 ◽  
Vol 3 (2) ◽  
pp. 19-41 ◽  
Author(s):  
Kusum Deep ◽  
Pinkey Chauhan ◽  
Millie Pant
Keyword(s):  
Optimal Solution ◽  
Complex Nature ◽  
Sigmoid Function ◽  
Loss Minimization ◽  
Physical Constraints ◽  
Trim Loss ◽  
Discrete Pso ◽  
Global Optimal ◽  
Power Mutation ◽  
Different Levels

Trim loss minimization is the most common problem that arises during the cutting process, when products with variable width or length are to be produced in bulk to satisfy customer demands from limited available/stocked materials. The aim is to minimize inevitable waste material. Under various environmental and physical constraints, the trim loss problem is highly constrained, non convex, nonlinear, and with integer restriction on all variables. Due to the highly complex nature of trim loss problem, it is not easy for manufacturers to select an appropriate method that provides a global optimal solution, satisfying all restrictions. This paper proposes a discrete variant of PSO, which embeds a mutation operator, namely power mutation during the position update stage. The proposed variant is named as Hybrid Discrete PSO (HDPSO). Binary variables in HDPSO are generated using sigmoid function with its domain derived from position update equation. Four examples with different levels of complexity are solved and results are compared with two recently developed GA and PSO variants. The computational studies indicate the competitiveness of proposed variant over other considered methods.

Do Arm Postures Vary With the Speed of Reaching?

1999 ◽  
Vol 81 (5) ◽  
pp. 2582-2586 ◽  
Author(s):  
Kiisa C. Nishikawa ◽  
Sara T. Murray ◽  
Martha Flanders
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Reaching Movements ◽  
Total Force ◽  
Joint Torques ◽  
Dynamic Factors ◽  
Human Arm ◽  
Wide Range ◽  
Dynamic Forces

Do arm postures vary with the speed of reaching? For reaching movements in one plane, the hand has been observed to follow a similar path regardless of speed. Recent work on the control of more complex reaching movements raises the question of whether a similar “speed invariance” also holds for the additional degrees of freedom. Therefore we examined human arm movements involving initial and final hand locations distributed throughout the three-dimensional (3D) workspace of the arm. Despite this added complexity, arm kinematics (summarized by the spatial orientation of the “plane of the arm” and the 3D curvature of the hand path) changed very little for movements performed over a wide range of speeds. If the total force (dynamic + quasistatic) had been optimized by the control system (e.g., as in a minimization of the change in joint torques or the change in muscular forces), the optimal solution would change with speed; slow movements would reflect the minimal antigravity torques, whereas fast movements would be more strongly influenced by dynamic factors. The speed-invariant postures observed in this study are instead consistent with a hypothesized optimization of only the dynamic forces.

Dynamic-joint-strength-based two-dimensional symmetric maximum weight-lifting simulation: Model development and validation

2020 ◽  
Vol 234 (7) ◽  
pp. 660-673
Author(s):  
Ritwik Rakshit ◽  
Yujiang Xiang ◽  
James Yang
Keyword(s):  
Joint Strength ◽  
Reaction Force ◽  
Weight Lifting ◽  
Ground Reaction Forces ◽  
Two Dimensional ◽  
Joint Angles ◽  
Maximum Weight ◽  
Strength Based ◽  
Optimization Formulation ◽  
Reaction Forces

This article presents an optimization formulation and experimental validation of a dynamic-joint-strength-based two-dimensional symmetric maximum weight-lifting simulation. Dynamic joint strength (the net moment capacity as a function of joint angle and angular velocity), as presented in the literature, is adopted in the optimization formulation to predict the symmetric maximum lifting weight and corresponding motion. Nineteen participants were recruited to perform a maximum-weight-box-lifting task in the laboratory, and kinetic and kinematic data including motion and ground reaction forces were collected using a motion capture system and force plates, respectively. For each individual, the predicted spine, shoulder, elbow, hip, knee, and ankle joint angles, as well as vertical and horizontal ground reaction force and box weight, were compared with the experimental data. Both root-mean-square error and Pearson’s correlation coefficient ( r) were used for the validation. The results show that the proposed two-dimensional optimization-based motion prediction formulation is able to accurately predict all joint angles, box weights, and vertical ground reaction forces, but not horizontal ground reaction forces.

scholarly journals Inverse and forward dynamics: models of multi–body systems

2003 ◽  
Vol 358 (1437) ◽  
pp. 1493-1500 ◽  
Author(s):  
E. Otten
Keyword(s):  
Inverse Dynamics ◽  
Temporal Patterns ◽  
Forward Dynamics ◽  
Muscle Forces ◽  
Complex Behaviour ◽  
Joint Torques ◽  
Advantages And Disadvantages ◽  
Reaction Forces ◽  
Internal Forces ◽  
Multi Body

Connected multi–body systems exhibit notoriously complex behaviour when driven by external and internal forces and torques. The problem of reconstructing the internal forces and/or torques from the movements and known external forces is called the ‘inverse dynamics problem’, whereas calculating motion from known internal forces and/or torques and resulting reaction forces is called the ‘forward dynamics problem’. When stepping forward to cross the street, people use muscle forces that generate angular accelerations of their body segments and, by virtue of reaction forces from the street, a forward acceleration of the centre of mass of their body. Inverse dynamics calculations applied to a set of motion data from such an event can teach us how temporal patterns of joint torques were responsible for the observed motion. In forward dynamics calculations we may attempt to create motion from such temporal patterns, which is extremely difficult, because of the complex mechanical linkage along the chains forming the multi–body system. To understand, predict and sometimes control multi–body systems, we may want to have mathematical expressions for them. The Newton–Euler, Lagrangian and Featherstone approaches have their advantages and disadvantages. The simulation of collisions and the inclusion of muscle forces or other internal forces are discussed. Also, the possibility to perform a mixed inverse and forward dynamics calculation are dealt with. The use and limitations of these approaches form the conclusion.

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