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The control of stable postures in the multijoint arm
J McIntyre1, F A Mussa-Ivaldi, E Bizzi
1Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139-4307, USA.
Experimental Brain Research
|July 1, 1996
Summary
Human limb stiffness is controlled by muscles and joints to maintain stability against external forces. Multijoint muscles play a key role in this neuro-musculo-skeletal system
Area of Science:
- Biomechanics
- Neuroscience
- Robotics
Background:
- Limb stiffness arises from muscle/joint elasticity, geometry, and neural control.
- Effective stiffness of nonlinear systems like the arm depends on external forces and actuator properties.
Purpose of the Study:
- Analyze factors influencing limb stiffness, including external forces.
- Investigate central nervous system (CNS) strategies for controlling limb stiffness and stability.
- Propose and simulate strategies for limb stability control.
Main Methods:
- Computer simulations to model limb stiffness and stability control strategies.
- Experimental validation using human subjects applying external forces.
- Analysis of muscle properties and their role in multijoint limb control.
Main Results:
- Human subjects increased joint stiffness to maintain stability under external forces.
- Multijoint muscles provide essential mechanical couplings for stability.
- A local strategy where muscle stiffness increases with force can achieve limb stability.
Conclusions:
- The neuro-musculo-skeletal system utilizes multijoint muscles for global stability control via local strategies.
- Understanding limb stiffness control is crucial for fields like robotics and rehabilitation.
- Passive local strategies involving muscle force can effectively manage limb stability.