scholarly journals Smart switching in feedforward control of grip force during manipulation of elastic objects

2017 ◽  
Author(s):  
Olivier White ◽  
Amir Karniel ◽  
Raz Leib ◽  
Charalambos Papaxanthis ◽  
Marie Barbiero ◽  
...  
Keyword(s):  
Control Systems ◽  
Grip Force ◽  
Feedforward Control ◽  
Load Force ◽  
Switching Systems ◽  
State Variables ◽  
Discrete State ◽  
Research Questions ◽  
New Research ◽  
The Brain

AbstractSwitching systems are common in artificial control systems. Here, we suggest that the brain adopts a switched feedforward control of grip forces during manipulation of objects. We measured how participants modulated grip force when interacting with soft and rigid virtual springs when stiffness varied nearly continuously between trials. We identified a sudden phase transition between two forms of feedforward control that differed in the timing of the synchronization between the anticipated load force and the applied grip force. The switch occurred several trials after a threshold stiffness level. These results suggest that in the control of grip force, the brain acts as a switching control system. This opens new research questions as to the nature of the discrete state variables that drive the switching.

Maintaining Grip: Anticipatory and Reactive EEG Responses to Load Perturbations

2008 ◽  
Vol 99 (2) ◽  
pp. 545-553 ◽  
Author(s):  
D. Kourtis ◽  
H. F. Kwok ◽  
N. Roach ◽  
A. M. Wing ◽  
P. Praamstra
Keyword(s):  
Grip Force ◽  
Precision Grip ◽  
Reflex Response ◽  
Load Force ◽  
Brain Potentials ◽  
Long Latency ◽  
Long Latency Reflex ◽  
The Brain ◽  
Load Perturbations ◽  
Predictable Condition

Previous behavioral work has shown the existence of both anticipatory and reactive grip force responses to predictable load perturbations, but how the brain implements anticipatory control remains unclear. Here we recorded electroencephalographs while participants were subjected to predictable and unpredictable external load perturbations. Participants used precision grip to maintain the position of an object perturbed by load force pulses. The load perturbations were either distributed randomly over an interval 700- to 4,300-ms (unpredictable condition) or they were periodic with interval 2,000 ms (predictable condition). Preparation for the predictable load perturbation was manifested in slow preparatory brain potentials and in electromyographic and force signals recorded concurrently. Preparation modulated the long-latency reflex elicited by load perturbations with a higher amplitude reflex response for unpredictable compared with predictable perturbations. Importantly, this modulation was also reflected in the amplitude of sensorimotor cortex potentials just preceding the long-latency reflex. Together, these results support a transcortical pathway for the long-latency reflex and a central modulation of the reflex grip force response.

Development of Reading Remediation for Dyslexic Individuals

2016 ◽  
Vol 224 (4) ◽  
pp. 240-246 ◽  
Author(s):  
Mélanie Bédard ◽  
Line Laplante ◽  
Julien Mercier
Keyword(s):  
20Th Century ◽  
Scientific Literature ◽  
Behavioral Data ◽  
Educational Neuroscience ◽  
Reading Remediation ◽  
Functional Brain ◽  
Neurophysiological Data ◽  
Brain Correlates ◽  
Research Questions ◽  
The Brain

Abstract. Dyslexia is a phenomenon for which the brain correlates have been studied since the beginning of the 20th century. Simultaneously, the field of education has also been studying dyslexia and its remediation, mainly through behavioral data. The last two decades have seen a growing interest in integrating neuroscience and education. This article provides a quick overview of pertinent scientific literature involving neurophysiological data on functional brain differences in dyslexia and discusses their very limited influence on the development of reading remediation for dyslexic individuals. Nevertheless, it appears that if certain conditions are met – related to the key elements of educational neuroscience and to the nature of the research questions – conceivable benefits can be expected from the integration of neurophysiological data with educational research. When neurophysiological data can be employed to overcome the limits of using behavioral data alone, researchers can both unravel phenomenon otherwise impossible to document and raise new questions.

The Cooking Ape: An Interview with Richard Wrangham

2005 ◽  
Vol 5 (1) ◽  
pp. 29-37
Author(s):  
elisabeth townsend
Keyword(s):  
Social Relationships ◽  
Human Behavior ◽  
Homo Sapiens ◽  
Social Groups ◽  
Harvard University ◽  
Primate Research ◽  
Social Organizations ◽  
Cooked Food ◽  
New Research ◽  
The Brain

Humans: The Cooking Ape Perhaps the first to suggest that humans were cooking as early as 1.9 million years ago, Richard Wrangham shows through his new research and his imagination how and possibly when cooking changed humans dramatically. Wrangham, Harvard University primatologist and MacArthur Fellow, has been studying the evolution of human cooking. After 25 years of primate research at his site in Kibale, Uganda, Wrangham is best known for explaining the similarity and differences across species of primate social organizations. In Kibale, he has analyzed chimpanzees’ behavior: how it’s changed when they interact with the environment and how their social groups have evolved. In particular, he noticed how food changed their interactions with each other. Like that of chimps, human behavior has been affected by food, especially as they shifted from raw to cooked food. Moving from eating food as it was discovered to collecting edibles and cooking them altered our social relationships. Cooked food has changed Homo sapiens physically by making food more digestible thereby altering jaws, teeth, and guts, and providing more calories for more expensive organs such as the brain. Wrangham discusses when and how humans may have started using fire to cook food, what they cooked, and the transition from cooking in an outdoor fire to hearths and open ovens.

Effects of local and core body temperature on grip force modulation during movement-induced load force fluctuations

2008 ◽  
Vol 103 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Stephen S. Cheung ◽  
Luke F. Reynolds ◽  
Mark A. B. Macdonald ◽  
Constance L. Tweedie ◽  
Robin L. Urquhart ◽  
...  
Keyword(s):  
Body Temperature ◽  
Grip Force ◽  
Core Body Temperature ◽  
Load Force ◽  
Force Fluctuations ◽  
Force Modulation ◽  
Core Body

Optimal Dispatching of Electrical Sensors for Automatic Control

2013 ◽  
Vol 676 ◽  
pp. 246-250 ◽  
Author(s):  
Jian Liang Liu ◽  
Jian Yang ◽  
Wei Yi Liu
Keyword(s):  
Automatic Control ◽  
Control Systems ◽  
Prediction Performance ◽  
Prediction Algorithm ◽  
Bayesian Decision ◽  
Discrete State ◽  
Automatic Control Systems ◽  
Continuous State ◽  
Dispatching Algorithm ◽  
Better Than

In this paper, we consider an electrical sensor dispatching problem for automatic control systems(ACS). We propose an algorithm which selects one (or a group of) electrical sensor at each time from a set of electrical sensors. Then, the automatic control prediction algorithm computes the estimates of the continuous state and the discrete state of the ACS based on the observation from the selected electrical sensors. As the electrical sensor dispatching algorithm is designed such that the Bayesian decision risk is minimized, the true discrete state can be better identified. At the same time, the continuous state prediction performance of the proposed algorithm is better than that of automatic control prediction algorithms using only predetermined electrical sensors. Finally, our algorithm is validated though an illustrative target tracking example.

scholarly journals On route with harbor seals – how their senses contribute to orientation, navigation and foraging

Neuroforum ◽  
2018 ◽  
Vol 24 (4) ◽  
pp. A183-A195
Author(s):  
Frederike D. Hanke ◽  
Guido Dehnhardt
Keyword(s):  
Model Organism ◽  
Sensory Systems ◽  
Harbor Seals ◽  
Coastal Regions ◽  
Sea Lions ◽  
Research Questions ◽  
The Senses ◽  
New Research

Summary Summary: Seals and sea lions are well-oriented in their habitat, the coastal regions and oceans, and are, moreover, successful hunters. During their movements between haul-out places and foraging grounds as well as during foraging, the sensory systems of seals and sea lions provide useful information, although the animals, and thus their sensory systems, face considerable challenges in their habitat and due to their amphibious lifestyle. In this review, in the first chapter, we compiled and later (chapter 4) discuss the information on the senses of seals and sea lions in general and their specific adaptations to habitat and lifestyle in particular. We hereby focus on the senses of harbor seals. Harbor seals turned into a model organism regarding the sensory systems due to intensive sensory research of the last decades. In the second and third chapter, the sensory basics are put into the context of orientation, navigation, and foraging. This allows formulating new research questions, such as where and how the information from different senses is integrated.

Trajectory Tracking of Underactuated Multibody Systems

2011 ◽  
Author(s):  
Stefan Reichl ◽  
Wolfgang Steiner
Keyword(s):  
Trajectory Tracking ◽  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Feedforward Control ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Differential Algebraic Equations ◽  
State Variables ◽  
Algebraic Equations

This work presents three different approaches in inverse dynamics for the solution of trajectory tracking problems in underactuated multibody systems. Such systems are characterized by less control inputs than degrees of freedom. The first approach uses an extension of the equations of motion by geometric and control constraints. This results in index-five differential-algebraic equations. A projection method is used to reduce the systems index and the resulting equations are solved numerically. The second method is a flatness-based feedforward control design. Input and state variables can be parameterized by the flat outputs and their time derivatives up to a certain order. The third approach uses an optimal control algorithm which is based on the minimization of a cost functional including system outputs and desired trajectory. It has to be distinguished between direct and indirect methods. These specific methods are applied to an underactuated planar crane and a three-dimensional rotary crane.

Variable and intermittent grip force control in response to differing load force dynamics

2018 ◽  
Vol 237 (3) ◽  
pp. 687-703 ◽  
Author(s):  
Francis M. Grover ◽  
Patrick Nalepka ◽  
Paula L. Silva ◽  
Tamara Lorenz ◽  
Michael A. Riley
Keyword(s):  
Force Control ◽  
Grip Force ◽  
Load Force ◽  
Force Dynamics ◽  
Grip Force Control

Wrist Action Affects Precision Grip Force

1997 ◽  
Vol 78 (1) ◽  
pp. 271-280 ◽  
Author(s):  
Mary M. Werremeyer ◽  
Kelly J. Cole
Keyword(s):  
Grip Force ◽  
Precision Grip ◽  
Load Force ◽  
Myoelectric Activity ◽  
Resistive Load ◽  
Wrist Flexion ◽  
Wrist Extension ◽  
Hand Muscles ◽  
Force Pulse ◽  
Grasp Stability

Werremeyer, Mary M. and Kelly J. Cole. Wrist action affects precision grip force. J. Neurophysiol. 78: 271–280, 1997. When moving objects with a precision grip, fingertip forces normal to the object surface (grip force) change in parallel with forces tangential to the object (load force). We investigated whether voluntary wrist actions can affect grip force independent of load force, because the extrinsic finger muscles cross the wrist. Grip force increased with wrist angular speed during wrist motion in the horizontal plane, and was much larger than the increased tangential load at the fingertips or the reaction forces from linear acceleration of the test object. During wrist flexion the index finger muscles in the hand and forearm increased myoelectric activity; during wrist extension this myoelectric activity increased little, or decreased for some subjects. The grip force maxima coincided with wrist acceleration maxima, and grip force remained elevated when subjects held the wrist in extreme flexion or extension. Likewise, during isometric wrist actions the grip force increased even though the fingertip loads remained constant. A grip force “pulse” developed that increased with wrist force rate, followed by a static grip force while the wrist force was sustained. Subjects could not suppress the grip force pulse when provided visual feedback of their grip force. We conclude that the extrinsic hand muscles can be recruited to assist the intended wrist action, yielding higher grip-load ratios than those employed with the wrist at rest. This added drive to hand muscles overcame any loss in muscle force while the extrinsic finger flexors shortened during wrist flexion motion. During wrist extension motion grip force increases apparently occurred from eccentric contraction of the extrinsic finger flexors. The coactivation of hand closing muscles with other wrist muscles also may result in part from a general motor facilitation, because grip force increased during isometric knee extension. However, these increases were related weakly to the knee force. The observed muscle coactivation, from all sources, may contribute to grasp stability. For example, when transporting grasped objects, upper limb accelerations simultaneously produce inertial torques at the wrist that must be resisted, and inertial loads at the fingertips from the object that must be offset by increased grip force. The muscle coactivation described here would cause similarly timed pulses in the wrist force and grip force. However, grip-load coupling from this mechanism would not contribute much to grasp stability when small wrist forces are required, such as for slow movements or when the object's total resistive load is small.

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