Trajectory Planning of Spine Motion During Flexion Using a Stability-Based Optimization

2010 ◽  
Author(s):  
Majid Khorsand Vakilzadeh ◽  
Hassan Salarieh ◽  
Mohsen Asghari ◽  
Mohamad Parnianpour
Keyword(s):  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Inverse Dynamics ◽  
Joint Stiffness ◽  
Static Stability ◽  
Computational Method ◽  
Muscle Activation Patterns ◽  
Spine Motion ◽  
The Stability ◽  
The Many

A central problem in motor control is to understand how the many biomechanical degrees of freedom are coordinated to achieve a goal. A common assumption is that Central Nervous System (CNS) would minimize a performance index to achieve this goal which is called objective function. In this paper, two popular objective functions are utilized to design the optimal trajectory of trunk movements. A 3D computational method incorporated with 18 anatomically oriented muscles is used to simulate human trunk system. Inverse dynamics allows us to compute torque which is generated around Lumbosacral joint. This torque is divided among muscles by static stability-based optimization. Trunk movement from the upright standing to 30 degrees of flexion is simulated based on this method. Incorporation of the stability condition with the static optimization resulted in an increase of antagonistic activities which would increase the joint stiffness around the Lumbosacral joint in response to gravity perturbation. Results would shed light on the interaction mechanisms in muscle activation patterns, seen in various performance indices.

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.

scholarly journals The Central Nervous System Does Not Minimize Energy Cost in Arm Movements

2010 ◽  
Vol 104 (6) ◽  
pp. 2985-2994 ◽  
Author(s):  
Dinant A. Kistemaker ◽  
Jeremy D. Wong ◽  
Paul L. Gribble
Keyword(s):  
Force Field ◽  
Energy Cost ◽  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Arm Movements ◽  
Dominant Factor ◽  
Minimal Energy ◽  
Null Field ◽  
Muscle Activation Patterns ◽  
Point To Point

It has been widely suggested that the many degrees of freedom of the musculoskeletal system may be exploited by the CNS to minimize energy cost. We tested this idea by having subjects making point-to-point movements while grasping a robotic manipulandum. The robot created a force field chosen such that the minimal energy hand path for reaching movements differed substantially from those observed in a null field. The results show that after extended exposure to the force field, subjects continued to move exactly as they did in the null field and thus used substantially more energy than needed. Even after practicing to move along the minimal energy path, subjects did not adapt their freely chosen hand paths to reduce energy expenditure. The results of this study indicate that for point-to-point arm movements minimization of energy cost is not a dominant factor that influences how the CNS arrives at kinematics and associated muscle activation patterns.

scholarly journals Musculoskeletal Analysis of Driving Fatigue: The Influence of Seat Adjustments

2013 ◽  
Vol 10 ◽  
pp. 373-378 ◽  
Author(s):  
Noor Aliah binti Abdul Majid ◽  
Mohd Fareez Edzuan Abdullah ◽  
Mohd Syahmi Jamaludin ◽  
Mitsuo Notomi ◽  
John Rasmussen
Keyword(s):  
Human Body ◽  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Inverse Dynamics ◽  
Spring Stiffness ◽  
Car Seat ◽  
Joint Forces ◽  
Rigid Body Model ◽  
Driving Fatigue ◽  
Anybody Modeling System

Main causes for discomfort experienced by vehicle drivers during driving were investigated using a rigid-body model originally developed in the AnyBody Modeling System [. The interactions between the human body and the car-seat in various combinations of seat-pan/backrest inclinations and the effect of pedal spring stiffness were analyzed using an inverse dynamics approach. To deal with the muscle redundancy problem, (i.e. the problem with the human-body containing more muscles than necessary to drive its degrees of freedom) a minimum-fatigue criterion [ was utilized. The results show that various seat adjustments (e.g., seat-pan and backrest inclinations) and the pedal spring stiffness have complex influences on the muscle activation and spinal joint forces of the human body. From the results, an optimal adjustment for the car-seat is proposed, i.e. the backrest inclination is 10° and the seat-pan inclination is between 0o to 5 o. This study can in general capture the overall interactions between human body and environment (i.e. the maximum muscle activity and spine forces), which is thought to be the factors of driving fatigue.

scholarly journals Development of a Musculoskeletal Model of Hyolaryngeal Elements for Understanding Pharyngeal Swallowing Mechanics

2020 ◽  
Vol 10 (18) ◽  
pp. 6276
Author(s):  
Takuya Hashimoto ◽  
Mariko Urabe ◽  
Foo Chee-Sheng ◽  
Atsuko Murakoshi ◽  
Takahiro Kikuchi ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Hyoid Bone ◽  
Muscle Activation ◽  
Inverse Dynamics ◽  
Thyroid Cartilage ◽  
Musculoskeletal Model ◽  
Muscle Activation Patterns ◽  
Ct Data ◽  
Pharyngeal Swallowing ◽  
Neuromuscular Coordination

A detailed understanding of muscle activity in human swallowing would provide insights into the complex neuromuscular coordination underlying swallowing. The purpose of this study was to introduce musculoskeletal analysis to investigate muscle activities involved in swallowing as there are limitations on studying comprehensive muscle activation patterns by conventional methods such as electromyography (EMG) measurement. A musculoskeletal model of swallowing was newly developed based on the skeletal model made from CT data of a healthy volunteer. Individual muscle forces were predicted in pharyngeal swallowing by inverse dynamics’ computations with static optimization, in which the typical trajectories of the hyoid bone and thyroid cartilage analyzed from videofluoroscopic (VF) data of the volunteer were used. The results identified the contribution of individual muscles in pharyngeal swallowing in relation to the movements of the hyoid bone and thyroid cartilage. The predicted sequence of muscle activity showed a qualitative agreement with salient features in previous studies with fine wire EMG measurements. This method, if validated further by imaging and EMG studies, enables studying a broader range of neuromuscular coordination in swallowing. The proposed method offers an avenue to understanding the physiological mechanisms of swallowing and could become useful to evaluate rehabilitation effects on dysphagia.

scholarly journals Reciprocal and coactivation commands are not sufficient to describe muscle activation patterns

1995 ◽  
Vol 18 (4) ◽  
pp. 754-755 ◽  
Author(s):  
C. C. A. M. Gielen ◽  
B. van Bolhuis
Keyword(s):  
Muscle Activation ◽  
Joint Stiffness ◽  
Isometric Contractions ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Relative Activation

AbstractRecent results have shown that the relative activation of muscles is different for isometric contractions and for movements. These results exclude an explanation of muscle activation patterns by a combination ofreciprocal and coactivation commands. These results also indicate that joint stiffness is not uniquely determined and that it may be different for isometric contractions and movements.

scholarly journals Simultaneous control of natural and extra degrees of freedom by isometric force and electromyographic activity in the muscle-to-force null space

2022 ◽  
Author(s):  
Sergio Gurgone ◽  
Daniele Borzelli ◽  
Paolo De Pasquale ◽  
Denise J Berger ◽  
Tommaso Lisini Baldi ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Null Space ◽  
Isometric Force ◽  
Individual Variability ◽  
Electromyographic Activity ◽  
Simultaneous Generation ◽  
Muscle Activation Patterns ◽  
Simultaneous Control ◽  
End Effectors

Abstract Objective. Muscle activation patterns in the muscle-to-force null space, i.e., patterns that do not generate task-relevant forces, may provide an opportunity for motor augmentation by allowing to control additional end-effectors simultaneously to natural limbs. Here we tested the feasibility of muscular null space control for augmentation by assessing simultaneous control of natural and extra degrees of freedom. Approach. We instructed eight participants to control translation and rotation of a virtual 3D end-effector by simultaneous generation of isometric force at the hand and null space activity extracted in real-time from the electromyographic signals recorded from 15 shoulder and arm muscles. First, we identified the null space components that each participant could control more naturally by voluntary co-contraction. Then, participants performed several blocks of a reaching and holding task. They displaced an ellipsoidal cursor to reach one of nine targets by generating force, and simultaneously rotated the cursor to match the target orientation by activating null space components. We developed an information-theoretic metric, an index of difficulty defined as the sum of a spatial and a temporal term, to assess individual null space control ability for both reaching and holding. Main Results. On average, participants could reach the targets in most trials already in the first block (72%) and they improved with practice (maximum 93%) but holding performance remained lower (maximum 43%). As there was a high inter-individual variability in performance, we performed a simulation with different spatial and temporal task conditions to estimate those for which each individual participants would have performed best. Significance. Muscular null space control is feasible and may be used to control additional virtual or robotics end-effectors. However, decoding of motor commands must be optimized according to individual null space control ability.

EMG-Assisted Neuromusculoskeletal Models Can Estimate Physiological Muscle Activations and Joint Moments Across the Neck Before Impacts

2021 ◽  
Author(s):  
Pavlos Silvestros ◽  
Claudio Pizzolato ◽  
David G. Lloyd ◽  
Ezio Preatoni ◽  
Harinderjit S. Gill ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Muscle Activation ◽  
Inverse Dynamics ◽  
A Priori ◽  
Neck Muscle ◽  
Joint Moments ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Flexion Extension ◽  
Muscle Activations

Abstract Knowledge of neck muscle activation strategies prior to sporting impacts is crucial for investigating mechanisms of severe spinal injuries. However, measurement of muscle activations during impacts is experimentally challenging and computational estimations are not often guided by experimental measurements. We investigated neck muscle activations prior to impacts with the use of electromyography (EMG)-assisted neuromusculoskeletal models. Kinematics and EMG recordings from four major neck muscles of a rugby player were experimentally measured during rugby activities. A subject-specific musculoskeletal model was created with muscle parameters informed from MRI measurements. The model was used in the Calibrated EMG-Informed Neuromusculoskeletal Modelling toolbox and three neural solutions were compared: i) static optimisation (SO), ii) EMG-assisted (EMGa) and iii) MRI-informed EMG-assisted (EMGaMRI). EMGaMRI and EMGa significantly (p¡0.01) outperformed SO when tracking cervical spine net joint moments from inverse dynamics in flexion/extension (RMSE = 0.95, 1.14 and 2.32 Nm) but not in lateral bending (RMSE = 1.07, 2.07 and 0.84 Nm). EMG-assisted solutions generated physiological muscle activation patterns and maintained experimental co-contractions significantly (p¡0.01) outperforming SO, which was characterised by saturation and non-physiological "on-off" patterns. This study showed for the first time that physiological neck muscle activations and cervical spine net joint moments can be estimated without assumed a priori objective criteria prior to impacts. Future studies could use this technique to provide detailed initial loading conditions for theoretical simulations of neck injury during impacts.

A Limited Set of Muscle Synergies for Force Control During a Postural Task

2005 ◽  
Vol 93 (1) ◽  
pp. 609-613 ◽  
Author(s):  
Lena H. Ting ◽  
Jane M. Macpherson
Keyword(s):  
Degrees Of Freedom ◽  
Neural Control ◽  
Muscle Activation ◽  
Balance Control ◽  
Computational Techniques ◽  
Muscle Synergies ◽  
Support Surface ◽  
Muscle Activation Patterns ◽  
Automatic Postural Response ◽  
Postural Responses

Recently developed computational techniques have been used to reduce muscle activation patterns of high complexity to a simple synergy organization and to bring new insights to the long-standing degrees of freedom problem in motor control. We used a nonnegative factorization approach to identify muscle synergies during postural responses in the cat and to examine the functional significance of such synergies for natural behaviors. We hypothesized that the simplification of neural control afforded by muscle synergies must be matched by a similar reduction in degrees of freedom at the biomechanical level. Electromyographic data were recorded from 8–15 hindlimb muscles of cats exposed to 16 directions of support surface translation. Results showed that as few as four synergies could account for >95% of the automatic postural response across all muscles and all directions. Each synergy was activated for a specific set of perturbation directions, and moreover, each was correlated with a unique vector of endpoint force under the limb. We suggest that, within the context of active balance control, postural synergies reflect a neural command signal that specifies endpoint force of a limb.

Bioaeroservoelastic Analysis of Involuntary Rotorcraft-Pilot Interaction

2014 ◽  
Vol 9 (3) ◽  
Author(s):  
Pierangelo Masarati ◽  
Giuseppe Quaranta
Keyword(s):  
Muscle Activation ◽  
Inverse Dynamics ◽  
Transfer Functions ◽  
Biomechanical Model ◽  
Coupled System ◽  
Multibody Modeling ◽  
Activation Patterns ◽  
Pilot Model ◽  
The Stability ◽  
Muscular Activation

This work presents the integration of a detailed biomechanical model of the arm of a helicopter pilot and an equivalently detailed aeroservoelastic model of a helicopter, resulting in what has been called a ‘bioaeroservoelastic’ analysis. The purpose of this analysis is to investigate potential adverse interactions, called rotorcraft-pilot couplings, between the aeroservoelastic system and the controls involuntarily introduced by the pilot into the control system in response to rotorcraft vibrations transmitted to the pilot through the cockpit: the so-called biodynamic feedthrough. The force exerted by the pilot on the controls results from the activation of the muscles of the arms according to specific patterns. The reference muscular activation value as a function of the prescribed action on the controls is computed using an inverse kinetostatics/inverse dynamics approach. A first-order quasi-steady correction is adopted to mimic the reflexive contribution to muscle activation. Muscular activation is further augmented by activation patterns that produce elementary actions on the control inceptors. These muscular activation patterns, inferred using perturbation analysis, are applied to control the aircraft through the pilot's limbs. The resulting biomechanical pilot model is applied to the aeroservoelastic analysis of a helicopter model expressly developed within the same multibody modeling environment to investigate adverse rotorcraft pilot couplings. The model consists of the detailed aeroelastic model of the main rotor, using nonlinear beams and blade element/momentum theory aerodynamics, a component mode synthesis model of the airframe structural dynamics, and servoactuator dynamics. Results in terms of the stability analysis of the coupled system are presented in comparison with analogous results obtained using biodynamic feedthrough transfer functions identified from experimental data.

Periodic Control in a Stick Balancing Problem

2019 ◽  
Author(s):  
Laszlo Bencsik ◽  
Tamas Insperger
Keyword(s):  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Control Mechanism ◽  
Control Process ◽  
Inverted Pendulum Model ◽  
Human Balancing ◽  
Control Goal ◽  
The Stability ◽  
Definition Of ◽  
Control Forces

Abstract Understanding the human balancing is a fundamental question. Investigation of simple tasks can help in this challenging problem. In order to describe the nature of the underlying control mechanism, first of all, the balancing force has to be determined. As a second step one can identify the behaviour of the controller. There are two main problems in the model of the whole control process of balancing, time-delay is unknown and the exact mathematical definition of the control goal is also not known. The explanation for this latter issue the classical inverted pendulum model has 2DoF but only one control forces exists, thus it can be handled as a typical underactuated mechanical system. In under-actuated systems the task of inverse dynamics is not well defined. Some degrees-of-freedom cannot directly be controlled, and the corresponding generalized coordinates depend on the system dynamics only. In this study we model the control mechanism as a time periodically (i.e. clock-driven) switched controller. We investigate the stability properties of the closed-loop system. We show a periodically switched controlled which can be a possible model of human balancing.

Sign in / Sign up

Export Citation Format

Share Document