Use of self-selected postures to regulate multi-joint stiffness during unconstrained tasks
| Autor: | Matthew A. Krutky, Randy D. Trumbower, Bing-Shiang Yang, Eric J. Perreault |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Adult
Male Rotation Posture lcsh:Medicine Kinematics Degrees of freedom (mechanics) Models Biological 050105 experimental psychology Task (project management) 03 medical and health sciences Young Adult 0302 clinical medicine Imaging Three-Dimensional Neuroscience/Motor Systems Control theory Task Performance and Analysis medicine Humans 0501 psychology and cognitive sciences lcsh:Science Motor skill Haptic technology ComputingMethodologies_COMPUTERGRAPHICS Physics Multidisciplinary Neuroscience/Behavioral Neuroscience business.industry 05 social sciences lcsh:R Motor control Stiffness Robotics Biomechanical Phenomena Motor Skills Arm lcsh:Q Female Joints Artificial intelligence medicine.symptom business 030217 neurology & neurosurgery Research Article Neuroscience |
| Zdroj: | PLoS ONE PLoS ONE, Vol 4, Iss 5, p e5411 (2009) |
| ISSN: | 1932-6203 |
| Popis: | Background: The human motor system is highly redundant, having more kinematic degrees of freedom than necessary to complete a given task. Understanding how kinematic redundancies are utilized in different tasks remains a fundamental question in motor control. One possibility is that they can be used to tune the mechanical properties of a limb to the specific requirements of a task. For example, many tasks such as tool usage compromise arm stability along specific directions. These tasks only can be completed if the nervous system adapts the mechanical properties of the arm such that the arm, coupled to the tool, remains stable. The purpose of this study was to determine if posture selection is a critical component of endpoint stiffness regulation during unconstrained tasks. Methodology/Principal Findings: Three-dimensional (3D) estimates of endpoint stiffness were used to quantify limb mechanics. Most previous studies examining endpoint stiffness adaptation were completed in 2D using constrained postures to maintain a non-redundant mapping between joint angles and hand location. Our hypothesis was that during unconstrained conditions, subjects would select arm postures that matched endpoint stiffness to the functional requirements of the task. The hypothesis was tested during endpoint tracking tasks in which subjects interacted with unstable haptic environments, simulated using a 3D robotic manipulator. We found that arm posture had a significant effect on endpoint tracking accuracy and that subjects selected postures that improved tracking performance. For environments in which arm posture had a large effect on tracking accuracy, the self-selected postures oriented the direction of maximal endpoint stiffness towards the direction of the unstable haptic environment. Conclusions/Significance: These results demonstrate how changes in arm posture can have a dramatic effect on task performance and suggest that postural selection is a fundamental mechanism by which kinematic redundancies can be exploited to regulate arm stiffness in unconstrained tasks. |
| Databáze: | OpenAIRE |
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