OPTIMIZATION-BASED DYNAMIC PREDICTION OF HUMAN POSTURAL RESPONSE UNDER TILTING OF BASE OF SUPPORT

2012 ◽  
Vol 09 (02) ◽  
pp. 1250011
Author(s):  
DAVOOD NADERI ◽  
MOHSEN SADEGHI-MEHR ◽  
BEHNAM MIRIPOUR FARD
Keyword(s):  
Optimization Problem ◽  
Sagittal Plane ◽  
Base Plate ◽  
Performance Measure ◽  
Joint Torque ◽  
Skeletal Structure ◽  
Data Simulation ◽  
Dynamic Prediction ◽  
Computational Procedures ◽  
Base Of Support

The purpose of this paper is to study formulations and computational procedures for prediction of natural human response to tilting of its base of support. The human skeletal structure is modeled as a five-segment, four-degree-of-freedom mechanical system standing on sinusoidally driven tilting platform in the sagittal plane. The problem is formulated based on predictive dynamics method that leads to an optimization problem. The joint torque square is included in the performance measure and the dynamic stability is achieved by satisfying the vertical forces criterion. The constrained nonlinear optimization problem is solved using an algorithm based on the sequential quadratic programming (SQP) approach. The results which are joint trajectories and torques are characterized in terms of two main types of movement strategies observed in humans, namely, the ankle and hip strategies. Moreover, the effect of arms on the stability of the model is studied. The results obtained with the formulation are validated with the experimental data. Simulation results demonstrate the effectiveness of the proposed formulation in prediction of natural motion of human in response to tilting of the base plate.

Dynamic Optimization of Human Running With Analytical Gradients

2015 ◽  
Vol 10 (2) ◽  
Author(s):  
Hyun-Joon Chung ◽  
Jasbir S. Arora ◽  
Karim Abdel-Malek ◽  
Yujiang Xiang
Keyword(s):  
Human Subjects ◽  
Reaction Force ◽  
Performance Measure ◽  
Joint Torque ◽  
Upper Body ◽  
Human Model ◽  
Dynamic Prediction ◽  
Foot Strike ◽  
Analytical Gradients ◽  
Human Running

The optimization-based dynamic prediction of 3D human running motion is studied in this paper. A predictive dynamics method is used to formulate the running problem, and normal running is formulated as a symmetric and cyclic motion. Recursive Lagrangian dynamics with analytical gradients for all the constraints and objective function are incorporated in the optimization process. The dynamic effort is used as the performance measure, and the impulse at the foot strike is also included in the performance measure. The joint angle profiles and joint torque profiles are calculated for the full-body human model, and the ground reaction force (GRF) is determined. Several cause-and-effect cases are studied, and the formulation for upper-body yawing motion is proposed and simulated. Simulation results from this methodology show good correlation with experimental data obtained from human subjects and the existing literature.

scholarly journals Joint torque and velocity optimization for a redundant leg of quadruped robot

2017 ◽  
Vol 14 (5) ◽  
pp. 172988141773189 ◽  
Author(s):  
Taihui Zhang ◽  
Honglei An ◽  
Hongxu Ma
Keyword(s):  
Angular Velocity ◽  
Sagittal Plane ◽  
Load Capacity ◽  
Optimization Criterion ◽  
Quadruped Robot ◽  
Joint Torque ◽  
Quadratic Program ◽  
Hydraulic Actuator ◽  
Joint Torques ◽  
Physical Limitations

Hydraulic actuated quadruped robot similar to BigDog has two primary performance requirements, load capacity and walking speed, so that it is necessary to balance joint torque and joint velocity when designing the dimension of single leg and controlling its motion. On the one hand, because there are three joints per leg on sagittal plane, it is necessary to firstly optimize the distribution of torque and angular velocity of every joint on the basis of their different requirements. On the other hand, because the performance of hydraulic actuator is limited, it is significant to keep the joint torque and angular velocity in actuator physical limitations. Therefore, it is essential to balance the joint torque and angular velocity which have negative correlation under the condition of constant power of the hydraulic actuator. The main purpose of this article is to optimize the distribution of joint torques and velocity of a redundant single leg with joint physical limitations. Firstly, a modified optimization criterion combining joint torques with angular velocity that takes both support phase and flight phase into account is proposed, and then the modified optimization criterion is converted into a normal quadratic programming problem. A kind of recurrent neural network is used to solve the quadratic program problem. This method avoids tremendous matrix inversion and fits for time-varying system. The achieved optimized distribution of joint torques and velocity is useful for aiding mechanical design and the following motion control. Simulation results presented in this article confirm the efficiency of this optimization algorithm.

scholarly journals A NEURAL NETWORK SYSTEM WITH REINFORCEMENT LEARNING TO CONTROL A DYNAMIC ARM MODEL

2001 ◽  
Vol 13 (03) ◽  
pp. 117-123 ◽  
Author(s):  
ILKAY ULUSOY ◽  
MOHAMAD PARNIANPOUR ◽  
NECIP BERME ◽  
SHELDON R. SIMON
Keyword(s):  
Neural Network ◽  
Reinforcement Learning ◽  
Sagittal Plane ◽  
A Priori ◽  
General Pattern ◽  
Initial Position ◽  
Joint Torque ◽  
Network System ◽  
Neural Network System ◽  
Torque Values

A neural network system is presented for controlling a two-link dynamic arm model where the task is to move the arm from any initial position to any final position in the sagittal plane. The controller produces joint torque-lime profiles that begin and end with equilibrium values at the initial and final positions, respectively. A memory type neural network is trained by supervised learning methods to predict the joint's static equilibrium torque values corresponding to joint angles. A reinforcement learning network is used to determine the parameters needed for synthesis of the torque-time profiles for each joint. The reinforcement signal is computed based on the distance between the desired end point position and velocity and the states achieved based on the generated torque profiles. The general pattern of the torque-time plots is decided a priori according to the literature. The methods of training and an illustrative example of the algorithm's performance are presented.

Modeling of Human Lower Extremity Musculo-Skeletal Structure Using Bond Graph Approach

2007 ◽  
Author(s):  
Ali Selk Ghafari ◽  
Ali Meghdari ◽  
Gholam Reza Vossoughi
Keyword(s):  
Sagittal Plane ◽  
Equations Of Motion ◽  
Bond Graph ◽  
Skeletal Structure ◽  
Governing Equations ◽  
Straight Line ◽  
Proposed Model ◽  
In Series ◽  
Muscular Function ◽  
Mechanical Linkage

A vector bond graph approach for dynamic modeling of human musculo-skeletal system is addressed in this article. In the proposed model, human body is modeled as a ten-segment, nine degree of freedom, mechanical linkage, actuated by ten muscles in sagittal plane. The head, arm and torso (HAT) are modeled as a single rigid body. Interaction of the feet with the ground is modeled using a spring-damper unit placed under the sole of each foot. The path of each muscle is represented by a straight line. Each actuator is modeled as a three-element, Hill-type muscle in series with tendon. The governing equations of motion generated by the proposed method are equivalent to those developed with more traditional techniques. However the models can be more easily used in conjunction with control models of neuro-muscular function for the simulation of overall dynamic motor performance. In the proposed structure, segments can be easily added or removed. Such a model may have applications in clinical diagnosis and modeling of paraplegic patients during robotic-assisted walking.

An Optimal Design Method for Reducing Brake Squeal in Disc Brake Systems

2007 ◽  
Author(s):  
Toru Matsushima ◽  
Shinji Nishiwaki ◽  
Shintarou Yamasaki ◽  
Kazuhiro Izui ◽  
Masataka Yoshimura
Keyword(s):  
Optimal Design ◽  
High Performance ◽  
Optimization Problem ◽  
Design Method ◽  
Performance Measure ◽  
Disc Brake ◽  
Analysis Model ◽  
Brake Squeal ◽  
Element Analysis ◽  
Optimal Design Method

Minimizing brake squeal is one of the most important issues in the development of high performance braking systems. Recent advances in numerical analysis, such as finite element analysis, have enabled sophisticated analysis of brake squeal phenomena, but current design methods based on such numerical analyses still fall short in terms of providing concrete performance measures for minimizing brake squeal in high performance design drafts at the conceptual design phase. This paper proposes an optimal design method for disc brake systems that specifically aims to reduce brake squeal by appropriately modifying the shapes of the brake system components. First, the relationships between the occurrence of brake squeal and the geometry and characteristics of various components is clarified, using a simplified analysis model. Next, a new design performance measure is proposed for evaluating brake squeal performance and an optimization problem is then formulated using this performance measure as an objective function. The optimization problem is solved using Genetic Algorithms. Finally, a design example is presented to examine the features of the optimal solutions and confirm that the proposed method can yield useful design information for the development of high performance braking systems that minimize brake squeal.

Assisted Spatial Sit-to-Stand Prediction-Part 1: Virtual Healthy Elderly Individuals

2020 ◽  
pp. 1-30
Author(s):  
James Yang ◽  
Burak Ozsoy
Keyword(s):  
Sagittal Plane ◽  
Functional Independence ◽  
Left Knee ◽  
Joint Torque ◽  
Vertical Orientation ◽  
Healthy Elderly ◽  
Sit To Stand ◽  
The Difference ◽  
The Right ◽  
Kinematics And Kinetics

Abstract Sit-to-stand (STS) motion is a key determinant of functional independence for the senior people. This paper extends a predictive dynamics formulation previously reported to predict the assisted STS motion, i.e., the motion with a mechanical assistance, unilateral grab-rail bar which is placed on the right side of the virtual-individuals with a vertical orientation. The formulation is able to predict kinetics and kinematics not only in the sagittal plane, but also in frontal and transverse planes. Two different objective functions are tested: The first one is the dynamic effort and the second one is the dynamic effort plus the difference between right and left side support reaction forces. Results show that sagittal plane kinematics and kinetics are not affected by the introduction of the grab-rail bar, whereas some significant differences are seen in the medial/lateral and anterior/posterior components of kinematics and kinetics. The healthy elderly group places a priority to the stability during an assisted STS task. The placement of the grab-rail bar on the right side results in a significant decrease in the left knee joint torque. Results in this study are consistent with those reported from the literature.

Robust Design Using Preference Aggregation Methods

2003 ◽  
Author(s):  
Zhihuang Dai ◽  
Michael J. Scott ◽  
Zissimos P. Mourelatos
Keyword(s):  
Robust Design ◽  
Multicriteria Optimization ◽  
Optimization Problem ◽  
Performance Measure ◽  
Preference Aggregation ◽  
Weighted Sum ◽  
Aggregation Method ◽  
Nominal Performance ◽  
Multicriteria Optimization Problem

Robust design is a methodology for improving the quality of a product or process by minimizing the effect of variations in the inputs without eliminating the causes of those variations. In robust design, the best design is obtained by solving a multicriteria optimization problem, trading off the nominal performance against the minimization of the variation of the performance measure. Because these methods often combine the two criteria with a weighted sum or another fixed aggregation strategy, which are known to miss Pareto points, they may fail to obtain a desired design. To overcome this inadequacy, a more comprehensive preference aggregation method is combined into robust design. Two examples are presented to illustrate the effectiveness of the proposed method.

Optimization-Based Digital Human Dynamics: Santos™ Walking Backwards

2007 ◽  
Author(s):  
Hyun Jung Kwon ◽  
Yujiang Xiang ◽  
Salam Rahmatalla ◽  
R. Timothy Marler ◽  
Karim Abdel-Malek ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Problem ◽  
Joint Angle ◽  
Spline Interpolation ◽  
Performance Measure ◽  
Degree Of Freedom ◽  
Human Model ◽  
Entire Body ◽  
Joint Torques ◽  
Digital Human

An objective of this study is to simulate the backward walking motion of a full-body digital human model. The model consists of 55 degree of freedom – 6 degrees of freedom for global translation and rotation and 49 degrees of freedom representing the kinematics of the entire body. The resultant action of all the muscles at a joint is represented by the torque for each degree of freedom. The torques and angles at a joint are treated as unknowns in the optimization problem. The B-spline interpolation is used to represent the time histories of the joint angles and the well-established robotics formulation of the Denavit-Hartenberg method is used for kinematics analysis of the mechanical system. The recursive Lagrangian formulation is used to develop the equations of motion, and was chosen because of its known computational efficiency. The backwards walking problem is formulated as a nonlinear optimization problem. The control points of the B-splines for the joint angle profiles are treated as the design variables. For the performance measure, total dynamic effort that is represented as the integral of the sum of the squares of all the joint torques is minimized using a sequential quadratic programming algorithm. The solution is simulated in the Santos™ environment. Results of the optimization problem are the torque and joint angle profiles. The torques at the key joints and the ground reaction forces are compared to those for the forward walk in order to study the differences between the two walking patterns. Simulation results are approximately validated with the experimental data which is motion captured in the VSR Lab at the University of Iowa.

Kinematic and Kinetic Constraints on Arm, Trunk, and Leg Segments in Target-Reaching Movements

2005 ◽  
Vol 93 (1) ◽  
pp. 352-364 ◽  
Author(s):  
James S. Thomas ◽  
Daniel M. Corcos ◽  
Ziaul Hasan
Keyword(s):  
Degrees Of Freedom ◽  
Neural Control ◽  
Time Course ◽  
Sagittal Plane ◽  
Principal Component ◽  
Joint Torque ◽  
Trunk Flexion ◽  
Joint Torques ◽  
Joint Task ◽  
Task Conditions

We studied target reaching tasks involving not only the arms but also the trunk and legs, which necessitated some trunk flexion. Such tasks can be successfully completed using an infinite number of combinations of segment motions due to the inherent kinematic redundancy with the excessive degrees of freedom (DOFs). Sagittal plane motions of six segments (shank, thigh, pelvis, trunk, humerus, and forearm) and dynamic torques of six joints (ankle, knee, hip, lumbar, shoulder, and elbow) were analyzed separately by principal component (PC) analyses to determine if there was a commonality among the shapes of the respective waveforms. Additionally, PC analyses were used to probe for constraining relationships among the 1) relative magnitudes of segment excursions and 2) the peak-to-peak dynamic joint torques. In summary, at the kinematic level, the tasks are simplified by the use of a single common waveform for all segment excursions with 89.9% variance accounted for (VAF), but with less fixed relationships among the relative scaling of the magnitude of segment excursions (62.2% VAF). However, at the kinetic level, the time course of the dynamic joint torques are not well captured by a single waveform (72.7% VAF), but the tasks are simplified by relatively fixed relationships among the scaling of dynamic joint torque magnitudes across task conditions (94.7% VAF). Taken together, these results indicate that, while the effective DOFs in a multi-joint task are reduced differently at the kinematic and kinetic levels, they both contribute to simplifying the neural control of these tasks.

A Biomechanical Analysis of the Last Stride, Touchdown, and Takeoff Characteristics of the Men's Long Jump

1994 ◽  
Vol 10 (1) ◽  
pp. 61-78 ◽  
Author(s):  
Adrian Lees ◽  
Philip Graham-Smith ◽  
Neil Fowler
Keyword(s):  
Vertical Velocity ◽  
Sagittal Plane ◽  
Muscular Contraction ◽  
The Body ◽  
Biomechanical Analysis ◽  
Compression Phase ◽  
Performance Variables ◽  
Long Jump ◽  
Cine Film ◽  
Base Of Support

This study was concerned with the measurement of performance variables from competitors in the men's long jump final of the World Student Games held in Sheffield, England, in July 1991. Several performances of 10 finalists were recorded on cine film at 100 Hz. Resulting sagittal plane kinematic data were obtained for the last stride, touchdown, and takeoff for a total of 27 jumps. It was confirmed that takeoff velocity was a function of touchdown velocity, and that there was an increase in vertical velocity at the expense of a reduction of horizontal velocity. It was concluded that there was evidence for mechanisms which may be termed mechanical, biomechanical, and muscular. The former relates to the generation of vertical velocity by the body pivoting over the base of support during the compression phase, and a lifting of the arms and free leg during the lift phase; the second is the elastic reutilization of energy; and the third is the contribution by concentric muscular contraction.

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