Feedback control of the neuromusculoskeletal system in a forward dynamics simulation of stair locomotion

2009 ◽  
Vol 223 (6) ◽  
pp. 663-675 ◽  
Author(s):  
A Selk Ghafari ◽  
A Meghdari ◽  
G Vossoughi
Keyword(s):  
Feedback Control ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Human Movement ◽  
Stair Climbing ◽  
Dynamics Simulation ◽  
Forward Dynamics ◽  
Control Loops ◽  
The Stability

The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of pressure during locomotion. The parameters of the proposed controller were determined by employing the iterative feedback tuning approach to minimize tracking errors during forward dynamics simulation. Simultaneously, an inverse-dynamics-based optimization was employed to compute a set of desired musculotendon forces in the closed-loop simulation to resolve muscle redundancy. Quantitative comparisons of the simulation results with the experimental measurements and the reference muscles' activities illustrate the accuracy and efficiency of the proposed method during the stable ascending simulation.

INTERSEGMENTAL COORDINATION IN LOWER EXTREMITIES AND MULTI-SEGMENTAL SPINE DURING DIFFERENT ACTIVITIES OF DAILY LIVING

2017 ◽  
Vol 17 (07) ◽  
pp. 1740015
Author(s):  
DAIQI GUO ◽  
SHENGZHENG KUAI ◽  
WENYU ZHOU ◽  
XINYU GUAN ◽  
ZHENHUA LIAO ◽  
...  
Keyword(s):  
Activities Of Daily Living ◽  
Daily Living ◽  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Principal Component ◽  
Human Movement ◽  
Stair Climbing ◽  
Motion Pattern ◽  
Level Walking ◽  
Lower Lumbar

Background: Human movement consists of numerous degrees of freedom (DOF). How the nervous system (NS) computes the appropriate command to coordinate these DOFs to finish specific tasks is still hotly debated. One common way to simplify the redundant DOFs is to coordinate multiple DOFs by combining them into units or synergies. The present study aimed to investigate the kinematic complexity of five activities of daily living (ADLs) and to detect the amount of kinematic synergy during every ADL and the relationship of the motion pattern between these ADLs. Method: Twenty-six able-bodied male individuals performed level walking, stair climbing, trunk bending, ipsilateral pick-up and contralateral pick-up in sequence. The segmental excursion of the thorax, upper lumbar, lower lumbar, pelvis, thigh and shank was calculated. Principal component analysis (PCA) was applied to determine the motion pattern of every ADL. Result: In the sagittal plane, trunk bending, ipsilateral pick-up and contralateral pick-up could be simplified by using one principal component (PC) with more than 95% variance accounted for (VAF). In addition, the motion pattern of every PC was similar among the three ADLs. Moreover, the angles between the vectors representing the first PC of the three ADLs were all less than 10[Formula: see text]. Level walking and stair climbing needed at least two PCs to reach 95% VAF. In addition, the motion pattern was different between the two ADLs. Moreover, the angle between the first PC of the two ADLs was around 90[Formula: see text]. In the coronal plane, the five ADLs except contralateral pick-up arrived at 90% VAF with two PCs. The motion pattern and the angle between the first PC both demonstrated larger differences among the five ADLs. Conclusion: Two PCs were essential to represent level walking and stair climbing, indicating a complex control strategy used by the NS. Trunk bending, ipsilateral pick-up and contralateral pick-up could be described with one PC in the sagittal plane, showing a strong coupling and simple motion pattern. In addition, the motion pattern varied considerably among these ADLs. The outcomes of this study can help clinicians to select suitable ADLs for the patients with various joint or disc diseases and to conduct corresponding functional test and rehabilitation.

A compact stair-climbing wheelchair with two 3-DOF legs and a 1-DOF base

2016 ◽  
Vol 43 (2) ◽  
pp. 181-192 ◽  
Author(s):  
Chang-Hyuk Lee ◽  
Kyung-min Lee ◽  
Jehong Yoo ◽  
In-su Kim ◽  
Young-bong Bang
Keyword(s):  
Degrees Of Freedom ◽  
Flat Surface ◽  
Estimation Method ◽  
Stable Condition ◽  
Stair Climbing ◽  
Joint Power ◽  
Content Type ◽  
Flat Surfaces ◽  
Simple Estimation ◽  
The Stability

Purpose – The purpose of this paper is to describe a compact wheelchair, which has two 3-degrees of freedom (DOF) legs and a 1-DOF base (the total DOF of the leg system is 7) for stair-climbing, and wheels for flat surface driving. Design/methodology/approach – The proposed wheelchair climbs stairs using the two 3-DOF legs with boomerang-shaped feet. The leg mechanisms are folded into the compact wheelchair body when the wheelchair moves over flat surfaces. The authors also propose a simple estimation method of stair shape using laser distance sensors, and a dual motor driving system to increase joint power. Findings – The proposed wheelchair can climb arbitrary height and width stairs by itself, even when they are slightly curved. During climbing, the trajectory of the seat position is linear to guarantee the comfort of rider, and the wheelchair always keeps a stable condition to ensure the stability in an emergency stop. Originality/value – The wheelchair mechanism with foldable legs and driving wheels enables smooth stair climbing, efficient flat surface driving and additional useful motions such as standing and tilting.

Pointwise Optimal Control of Dynamical Systems Described by Constrained Coordinates

1999 ◽  
Vol 121 (4) ◽  
pp. 594-598 ◽  
Author(s):  
V. Radisavljevic ◽  
H. Baruh
Keyword(s):  
Optimal Control ◽  
Dynamical Systems ◽  
Feedback Control ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Differential Algebraic Equations ◽  
Control Law ◽  
Algebraic Equations ◽  
The Stability ◽  
The Mathematical Model

A feedback control law is developed for dynamical systems described by constrained generalized coordinates. For certain complex dynamical systems, it is more desirable to develop the mathematical model using more general coordinates then degrees of freedom which leads to differential-algebraic equations of motion. Research in the last few decades has led to several advances in the treatment and in obtaining the solution of differential-algebraic equations. We take advantage of these advances and introduce the differential-algebraic equations and dependent generalized coordinate formulation to control. A tracking feedback control law is designed based on a pointwise-optimal formulation. The stability of pointwise optimal control law is examined.

Dynamics of Serial Multibody Systems Using the Decoupled Natural Orthogonal Complement Matrices

1999 ◽  
Vol 66 (4) ◽  
pp. 986-996 ◽  
Author(s):  
S. K. Saha
Keyword(s):  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Equations Of Motion ◽  
Kinematic Chain ◽  
Rigid Bodies ◽  
Dynamic Equations ◽  
Orthogonal Complement ◽  
Forward Dynamics ◽  
Velocity Constraints

Constrained dynamic equations of motion of serial multibody systems consisting of rigid bodies in a serial kinematic chain are derived in this paper. First, the Newton-Euler equations of motion of the decoupled rigid bodies of the system at hand are written. Then, with the aid of the decoupled natural orthogonal complement (DeNOC) matrices associated with the velocity constraints of the connecting bodies, the Euler-Lagrange independent equations of motion are derived. The De NOC is essentially the decoupled form of the natural orthogonal complement (NOC) matrix, introduced elsewhere. Whereas the use of the latter provides recursive order n—n being the degrees-of-freedom of the system at hand—inverse dynamics and order n3 forward dynamics algorithms, respectively, the former leads to recursive order n algorithms for both the cases. The order n algorithms are desirable not only for their computational efficiency but also for their numerical stability, particularly, in forward dynamics and simulation, where the system’s accelerations are solved from the dynamic equations of motion and subsequently integrated numerically. The algorithms are illustrated with a three-link three-degrees-of-freedom planar manipulator and a six-degrees-of-freedom Stanford arm.

Estimation of Metabolical Costs for Human Locomotion

2005 ◽  
Author(s):  
Werner Schiehlen ◽  
Marko Ackermann
Keyword(s):  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Human Locomotion ◽  
Human Gait ◽  
Joint Torques ◽  
Gait Quality ◽  
Analysis Laboratory ◽  
Muscle Models

Metabolical energy is the chemical energy consumed by skeletal muscles to generate force. This quantity is useful to understand the comfort of human gait and to evaluate, in terms of effort required, the performance of devices or therapies designed to improve gait quality of persons presenting gait disorders. Firstly, this paper presents the frequently used estimations of energy expenditure based lonely on joint torques and mechanical costs obtained by inverse dynamics of passive and active walking devices. Secondly, a more advanced approach is discussed consisting of modeling the musculoskeletal system with Hill-type phenomenological muscle models and computing the metabolical expenditure adopting expressions recently proposed in the literature. As an example a musculoskeletal model of the lower limb in the sagittal plane consisting of thigh, shank and foot with three degrees of freedom and actuated by eight muscles is considered. This model is used to estimate metabolical costs for known normal gait kinematical data obtained in a gait analysis laboratory.

Walking Stability Analysis for a Biped Robot Considering Ground Condition

2013 ◽  
Vol 427-429 ◽  
pp. 1175-1178
Author(s):  
Ying Xu ◽  
Zhi Yuan Zeng
Keyword(s):  
Degrees Of Freedom ◽  
Biped Robot ◽  
Simulation Software ◽  
Dynamics Simulation ◽  
Design Data ◽  
Movement Characteristics ◽  
Lateral Plane ◽  
Stable Gait ◽  
The Stability ◽  
Ground Condition

With human characteristics of the structure of lower limb joints and simplify them, 12 degrees of freedom was equipped with for the lower extremities of biped walking robot. motion model is established and used to elaborate the movement characteristics in sagittal and lateral plane according to a particular mechanism of robot. The stability of robot in two or there dimensions is analyzed through ZMP principles and the calculation formula and measuring methods of corresponding ZMP are also concluded, Gait design data will be taken into the virtual prototype and make motion Simulation for gait, then get the simulation animation of walking straight, static turning and moves upstairs, This paper expounds the possibility of generating smooth walking trajectory with cubic interpolation. Using the dynamics simulation software to simulate the robot, the results show that the robot has the theory of stable gait, The control accuracy of joints position and the realization of desired purposes of the robot system.

Forward dynamics simulation of human walking employing an iterative feedback tuning approach

2008 ◽  
Vol 223 (3) ◽  
pp. 289-297 ◽  
Author(s):  
Selk A Ghafari ◽  
A Meghdari ◽  
G R Vossoughi
Keyword(s):  
Pid Controller ◽  
Closed Loop ◽  
Inverse Dynamics ◽  
Human Motion ◽  
Dynamics Simulation ◽  
Forward Dynamics ◽  
Tracking Errors ◽  
Stable Gait ◽  
Inverse Dynamics Analysis ◽  
Iterative Feedback

Inverse dynamics analysis as well as the generation of an optimal goal oriented human motion both lead to the problem of finding suitable activations of the redundant muscles involved. This paper employs an iterative feedback tuning approach to perform the forward dynamics simulation of the human musculoskeletal system during level walking. A modified form of the proportional-integral-derivative (PID) controller is proposed to stabilize the movement and provide tracking of problems of the desired lower extremity joint profiles. Controller parameters were determined iteratively using an optimization algorithm to minimize tracking errors during forward dynamics simulation. Static optimization was employed simultaneously to compute a set of desired musculotendon forces in the closed-loop simulation to resolve muscle redundancy. Quantitative comparisons of the simulation results with the gait experimental measurements and the reference muscle activity show the accuracy and efficiency of the proposed method to provide a stable gait.

scholarly journals Performance Analysis on Depth and Straight Motion Control based on Control Surface Combinations for Supercavitating Underwater Vehicle

2021 ◽  
Vol 24 (4) ◽  
pp. 435-448
Author(s):  
Beomyeol Yu ◽  
Hyemin Mo ◽  
Seungkeun Kim ◽  
Jong-Hyon Hwang ◽  
Jeong-Hoon Park ◽  
...  
Keyword(s):  
Motion Control ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Underwater Vehicle ◽  
Control Surface ◽  
Control Performance ◽  
Friction Resistance ◽  
Control Loops ◽  
The Stability ◽  
And Control

This study describes the depth and straight motion control performance depending on control surface combinations of a supercavitating underwater vehicle. When an underwater vehicle experiences supercavitation, friction resistance can be minimized, thus achieving the effect of super-high-speed driving. Six degrees of freedom modeling of the underwater vehicle are performed and the guidance and control loops are designed with not only a cavitator and an elevator, but also a rudder and a differential elevator to improve the stability of the roll and yaw axis. The control performance based on the combination of control surfaces is analyzed by the root-mean-square error for keeping depth and straight motion.

Coarse-Grained Molecular Dynamics Simulation of Lysozyme Protein Crystals

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Nafiseh Farhadian ◽  
Mojtaba Shariaty-Niassar ◽  
Kourosh Malek ◽  
Ali Maghari
Keyword(s):  
Molecular Dynamics ◽  
Degrees Of Freedom ◽  
Coarse Graining ◽  
Dynamics Simulation ◽  
Coarse Grained ◽  
Protein Crystal ◽  
Protein Crystals ◽  
Biological Phenomena ◽  
The Stability ◽  
Coarse Grained Molecular Dynamics

Many biological phenomena of interest occur on a time scale that is too great to be studied by atomistic simulations. The use of coarse-graining methods to represent a system can alleviate this restriction by reducing the number of degrees of freedom thus extending the time and length scale in molecular modeling. Coarse-grained molecular dynamics (CGMD) technique was employed to simulate diffusion of water in the nanopores of lysozyme protein crystals. Good agreement was obtained between the atomistic and CG simulations in view of the stability of the protein crystal structure and water transport properties. Our simulations demonstrate that the CG method is a suitable technique for simulation the solvent diffusion process in the lysozyme protein crystal and also can be a good technique to predict the behavior of solvent and solutes in the biological systems at longer length and time scales.

The Validity of Summing Lower Extremity Individual Joint Kinetic Measures

2005 ◽  
Vol 21 (2) ◽  
pp. 181-188 ◽  
Author(s):  
Sean P. Flanagan ◽  
George J. Salem
Keyword(s):  
Lower Extremity ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Human Movement ◽  
Joint Moment ◽  
Biomechanical Analysis ◽  
Lower Extremity Function ◽  
Single Measure ◽  
Work Task ◽  
Joint Kinetics

In the analysis of human movement, researchers often sum individual joint kinetics to obtain a single measure of lower extremity function. The extent to which these summed measures relate to the mechanical objectives of the task has not been formally validated. The criterion validity of these measures was established with comparisons to the mechanical objective of two multiple-joint tasks. For the Work task 18 participants performed a loaded barbell squat using 4 resistances while instrumented for biomechanical analysis. For the Power they performed 2 predetermined amounts of work at both self-selected and fast speeds. Using inverse dynamics techniques, the peak net joint moment (PM) was calculated bilaterally in the sagittal plane at the ankle, knee, and hip and was summed into a single measure. This measure was correlated with the task objectives using simple linear regression. Similar procedures were used for the average net joint moment (AM), peak (PP), and average (AP) net joint moment power, and the net joint moment impulse (IM) and work (IP). For the Work task all 6 measures were significantly correlated with the task objective, but only AM, PM, and IP had correlation coefficients above 0.90. For the Power task, IM was not significantly correlated with the task objective, and only AP had a correlation coefficient above 0.90. These findings indicate that the validity of summing individual kinetic measures depends on both the measure chosen and the mechanical objective of the task.

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