Muscle Synergy Constraints Improve Prediction of Knee Contact Force During Gait

2013 ◽  
Author(s):  
Benjamin J. Fregly ◽  
Jonathan P. Walter ◽  
Allison L. Kinney ◽  
Scott A. Banks ◽  
Darryl D. D’Lima ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Neural Control ◽  
Optimization Methods ◽  
Internal Force ◽  
Contact Forces ◽  
Muscle Synergy ◽  
Patient Specific ◽  
Joint Contact ◽  
Specific Muscle ◽  
Clinical Conditions

Knowledge of patient-specific muscle and joint contact forces during activities of daily living could improve the treatment of movement-related disorders (e.g., osteoarthritis, stroke, cerebral palsy, Parkinson’s disease). Unfortunately, it is currently impossible to measure these quantities directly under common clinical conditions, and calculation of these quantities using computer models is limited by the redundant nature of human neural control (i.e., more muscles than theoretically necessary to actuate the available degrees of freedom in the skeleton). Walking is a particularly important task to understand, since loss of mobility is associated with increased morbidity and decreased quality of life [1]. Though numerous musculoskeletal computer modeling studies have used optimization methods to resolve the neural control redundancy problem, these estimates remain unvalidated due to the lack of internal force measurements that can be used for validation purposes.

scholarly journals Can Measured Synergy Excitations Accurately Construct Unmeasured Muscle Excitations?

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Nicholas A. Bianco ◽  
Carolynn Patten ◽  
Benjamin J. Fregly
Keyword(s):  
Muscle Force ◽  
Human Movement ◽  
Optimization Methods ◽  
Contact Forces ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Large Set ◽  
Dimensional Representation ◽  
Joint Contact ◽  
Low Dimensional

Accurate prediction of muscle and joint contact forces during human movement could improve treatment planning for disorders such as osteoarthritis, stroke, Parkinson's disease, and cerebral palsy. Recent studies suggest that muscle synergies, a low-dimensional representation of a large set of muscle electromyographic (EMG) signals (henceforth called “muscle excitations”), may reduce the redundancy of muscle excitation solutions predicted by optimization methods. This study explores the feasibility of using muscle synergy information extracted from eight muscle EMG signals (henceforth called “included” muscle excitations) to accurately construct muscle excitations from up to 16 additional EMG signals (henceforth called “excluded” muscle excitations). Using treadmill walking data collected at multiple speeds from two subjects (one healthy, one poststroke), we performed muscle synergy analysis on all possible subsets of eight included muscle excitations and evaluated how well the calculated time-varying synergy excitations could construct the remaining excluded muscle excitations (henceforth called “synergy extrapolation”). We found that some, but not all, eight-muscle subsets yielded synergy excitations that achieved >90% extrapolation variance accounted for (VAF). Using the top 10% of subsets, we developed muscle selection heuristics to identify included muscle combinations whose synergy excitations achieved high extrapolation accuracy. For 3, 4, and 5 synergies, these heuristics yielded extrapolation VAF values approximately 5% lower than corresponding reconstruction VAF values for each associated eight-muscle subset. These results suggest that synergy excitations obtained from experimentally measured muscle excitations can accurately construct unmeasured muscle excitations, which could help limit muscle excitations predicted by muscle force optimizations.

Muscle and Contact Contributions to Inverse Dynamic Knee Loads During Gait

2009 ◽  
Author(s):  
Benjamin J. Fregly ◽  
Yi-Chung Lin ◽  
Jonathan P. Walter ◽  
Marcus G. Pandy ◽  
Scott A. Banks ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Degrees Of Freedom ◽  
Muscle Force ◽  
Human Movement ◽  
Contact Forces ◽  
Cartilage Defects ◽  
Inverse Dynamic ◽  
Joint Replacements ◽  
Joint Contact ◽  
Articular Cartilage Defects

Musculoskeletal computer models capable of predicting muscle and joint contact forces accurately during human movement could facilitate the design of improved joint replacements and new clinical treatments for articular cartilage defects or movement-related disorders [1]. A primary challenge to developing such predictions is the non-uniqueness of the calculated muscle forces, often referred to as the “muscle redundancy problem” [2]. Since more muscles act on the skeleton than the number of degrees of freedom in the skeleton, an infinite number of possible muscle force solutions exist.

scholarly journals Characterization of track geometric imperfections leading to maximal dynamic amplification of internal forces in railway bridges

2017 ◽  
Vol 10 (4) ◽  
pp. 937-956 ◽  
Author(s):  
P. G. C. Amaral ◽  
C. E. N. Mazzilli
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Internal Force ◽  
Contact Forces ◽  
Beam Model ◽  
Railway Bridges ◽  
Rail Line ◽  
Internal Forces ◽  
Dynamic Amplification ◽  
The Impact

ABSTRACT This paper resorts to a simplified dynamic analysis methodology for the study of vibrations in railway bridges produced by the passage of a typical passenger train, or EUT (Electric Unit Train). It starts from a model with fifteen degrees-of-freedom, namely vertical (bounce) and horizontal displacements (sway) and rotations about the longitudinal (roll), transverse (pitch) and vertical (yaw) axes. In this methodology, dynamic models of the train and the bridge are assumed to be initially uncoupled, yet being bound by the interaction train-bridge forces. Thus, the loads are evaluated for the train running on a rigid and fixed deck, considering geometric irregularities, different for each rail line, in both the vertical and horizontal track planes, as well as in the wheels. The contact forces are statically condensed at the vehicle’s centre of gravity and applied on a simplified 3D beam model. To represent the train passage over the bridge, functions are used to describe the interaction forces at each node of the beam model, as time evolves. Thus, it is possible to identify the dynamic response caused by the geometric irregularities and also evaluate the dynamic amplification obtained for any internal force, which is compared to the impact coefficient proposed by the Brazilian standards for the design of railway bridges (NBR 7187), used in quasi-static analysis. For the sake of an illustration, a thirty-six-metre-span concrete bridge with box girder section was considered. A study was carried out to find out the parameters of the irregularity functions that could potentially lead to maximal amplification of internal forces in the bridge.

scholarly journals In Vivo Knee Contact Force Prediction Using Patient-Specific Musculoskeletal Geometry in a Segment-Based Computational Model

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Ziyun Ding ◽  
Daniel Nolte ◽  
Chui Kit Tsang ◽  
Daniel J. Cleather ◽  
Angela E. Kedgley ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Contact Forces ◽  
Coefficient Of Determination ◽  
Patient Specific ◽  
Grand Challenge ◽  
Sit To Stand ◽  
Normal Gait ◽  
Musculoskeletal Models ◽  
Mean Square Errors

Segment-based musculoskeletal models allow the prediction of muscle, ligament, and joint forces without making assumptions regarding joint degrees-of-freedom (DOF). The dataset published for the “Grand Challenge Competition to Predict in vivo Knee Loads” provides directly measured tibiofemoral contact forces for activities of daily living (ADL). For the Sixth Grand Challenge Competition to Predict in vivo Knee Loads, blinded results for “smooth” and “bouncy” gait trials were predicted using a customized patient-specific musculoskeletal model. For an unblinded comparison, the following modifications were made to improve the predictions: further customizations, including modifications to the knee center of rotation; reductions to the maximum allowable muscle forces to represent known loss of strength in knee arthroplasty patients; and a kinematic constraint to the hip joint to address the sensitivity of the segment-based approach to motion tracking artifact. For validation, the improved model was applied to normal gait, squat, and sit-to-stand for three subjects. Comparisons of the predictions with measured contact forces showed that segment-based musculoskeletal models using patient-specific input data can estimate tibiofemoral contact forces with root mean square errors (RMSEs) of 0.48–0.65 times body weight (BW) for normal gait trials. Comparisons between measured and predicted tibiofemoral contact forces yielded an average coefficient of determination of 0.81 and RMSEs of 0.46–1.01 times BW for squatting and 0.70–0.99 times BW for sit-to-stand tasks. This is comparable to the best validations in the literature using alternative models.

Tibio-Femoral Contact Force During Gait: An Iterative Method Using EMG-Constrained Multi-Body Simulation and Finite Element Analysis

2013 ◽  
Author(s):  
Silvia Pianigiani ◽  
Friedl De Groote ◽  
Lennart Scheys ◽  
Pierre Gillen ◽  
Luc Labey ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Image Data ◽  
Contact Forces ◽  
Patient Specific ◽  
Optimization Approach ◽  
Element Analysis ◽  
Force Calculation

In this study, we present an innovative methodology (Figure 1) to calculate patient specific tibio-femoral (TF) contact forces by integrating medical image data, 3D skin-mounted marker trajectories, ground reaction forces, electromyography (EMG) data and finite element analysis (FEA). The muscle redundancy problem is solved through an EMG-constrained optimization approach. Calculated muscle forces are input to a FEA to calculate TF contact forces. Kinematics of the degrees of freedom (DOFs) of the knee that cannot be accurately assessed from the trajectories of skin-mounted markers, are estimated using a novel iterative procedure which combines muscle force calculation with dynamic FEA. The presented methodology is applied to analyze TF contact forces of a walking trial performed on an instrumented treadmill of which the speed was sequentially ramped up and down. The results presented in this abstract will be validated against the in-vivo measured TF contact forces.

scholarly journals A Hertzian Integrated Contact Model of the Total Knee Replacement Implant for the Estimation of Joint Contact Forces

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Tien Tuan Dao ◽  
Philippe Pouletaut
Keyword(s):  
Total Knee Replacement ◽  
Elastic Properties ◽  
Knee Replacement ◽  
Material Properties ◽  
Contact Forces ◽  
Contact Model ◽  
Patient Specific ◽  
Joint Contact ◽  
Total Knee

The prediction of lower limb muscle and contact forces may provide useful knowledge to assist the clinicians in the diagnosis as well as in the development of appropriate treatment for musculoskeletal disorders. Research studies have commonly estimated joint contact forces using model-based muscle force estimation due to the lack of a reliable contact model and material properties. The objective of this present study was to develop a Hertzian integrated contact model. Then, in vivo elastic properties of the Total Knee Replacement (TKR) implant were identified using in vivo contact forces leading to providing reliable material properties for modeling purposes. First, a patient specific rigid musculoskeletal model was built. Second, a STL-based implant model was designed to compute the contact area evolutions during gait motions. Finally, a Hertzian integrated contact model was defined for the in vivo identification of elastic properties (Young’s modulus and Poisson coefficient) of the instrumented TKR implant. Our study showed a potential use of a new approach to predict the contact forces without knowledge of muscle forces. Thus, the outcomes may lead to accurate and reliable prediction of human joint contact forces for new case study.

Dynamic Analysis and Configuration Design of a Two-Component Wave-Energy Absorber

2012 ◽  
Author(s):  
Christophe Cochet ◽  
Ronald W. Yeung
Keyword(s):  
Wave Energy ◽  
Degrees Of Freedom ◽  
Outer Cylinder ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Energy Extraction ◽  
Energy Absorber ◽  
Compound Cylinder ◽  
Motion Study ◽  
Heave Motion

The wave-energy absorber being developed at UC Berkeley is modeled as a moored compound cylinder, with an outer cylinder sliding along a tension-tethered inner cylinder. With rigid-body dynamics, it is first shown that the surge and pitch degrees of freedom are decoupled from the heave motion. The heaving motion of the outer cylinder is analyzed and its geometric proportions (radii and drafts ratios) are optimized for wave-energy extraction. Earlier works of Yeung [1] and Chau and Yeung [2,3] are used in the present heave-motion study. The coupled surge-pitch motion can be solved and can provide the contact forces between the cylinders. The concept of capture width is used to characterize the energy extraction: its maximization leads to optimal energy extraction. The methodology presented provides the optimal geometry in terms of non-dimensional proportions of the device. It is found that a smaller radius and deeper draft for the outer cylinder will lead to a larger capture width and larger resulting motion.

Functional Evaluation of a Personalized Orthosis for Knee Osteoarthritis - A Motion Capture Analysis

2021 ◽  
Author(s):  
Martin Huber ◽  
Matthew Eschbach ◽  
Kazem Kazerounian ◽  
Horea T. Ilies
Keyword(s):  
Knee Joint ◽  
Knee Osteoarthritis ◽  
Motion Capture ◽  
Inverse Dynamics ◽  
Statistical Significance ◽  
Knee Kinematics ◽  
Contact Forces ◽  
Patient Specific ◽  
Functional Evaluation ◽  
Shock Absorption

Abstract Knee osteoarthritis (OA) is a disease that compromises the cartilage inside the knee joint, resulting in pain and impaired mobility. Bracing is a common treatment, however currently prescribed braces cannot treat bicompartmental knee OA, fail to consider the muscle weakness that typically accompanies the disease, and utilize hinges that restrict the knee's natural biomechanics. We have developed and evaluated a brace which addresses these shortcomings. This process has respected three principal design goals: reducing the load experienced across the entire knee joint, generating a supportive moment to aid the muscles in shock absorption, and interfering minimally with gait kinematics. Load reduction is achieved via the compression of medial and lateral leaf springs, and magnetorheological dampers provide the supportive moment during knee loading. A novel, personalized joint mechanism replaces a traditional hinge to reduce interference with knee kinematics. Using motion capture gait analysis, we evaluated the basic functionality of a prototype device. We calculated, via inverse dynamics analysis, the reaction forces at the knee joint and the moments generated by the leg muscles during gait. Comparing these values between braced and unbraced trials allowed us to evaluate the system's effectiveness. Kinematic measurements showed the extent to which the brace interfered with natural gait characteristics. Of the three design goals: a reduction in knee contact forces was demonstrated; increased shock absorption was observed, but not to statistical significance; and natural gait was largely preserved. The techniques presented in this paper could lead to improved OA treatment through patient-specific braces.

scholarly journals Recent Design Optimization Methods for Energy-Efficient Electric Motors and Derived Requirements for a New Improved Method—Part 1

Proceedings ◽  
2018 ◽  
Vol 2 (22) ◽  
pp. 1400
Author(s):  
Johannes Schmelcher ◽  
Max Kleine Büning ◽  
Kai Kreisköther ◽  
Dieter Gerling ◽  
Achim Kampker
Keyword(s):  
Rare Earth ◽  
Design Optimization ◽  
Energy Efficient ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Optimization Problems ◽  
Computing Time ◽  
Optimization Methods ◽  
Electric Motors ◽  
Electric Cars

Energy-efficient electric motors are gathering an increased attention since they are used in electric cars or to reduce operational costs, for instance. Due to their high efficiency, permanent-magnet synchronous motors are used progressively more. However, the need to use rare-earth magnets for such high-efficiency motors is problematic not only in regard to the cost but also in socio-political and environmental aspects. Therefore, an increasing effort has to be put in finding the best design possible. The goals to achieve are, among others, to reduce the amount of rare-earth magnet material but also to increase the efficiency. In the first part of this multipart paper, characteristics of optimization problems in engineering and general methods to solve them are presented. In part two, different approaches to the design optimization problem of electric motors are highlighted. The last part will evaluate the different categories of optimization methods with respect to the criteria: degrees of freedom, computing time and the required user experience. As will be seen, there is a conflict of objectives regarding the criteria mentioned above. Requirements, which a new optimization method has to fulfil in order to solve the conflict of objectives will be presented in this last paper.

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