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Sit-to-stand-and-walk from 120% Knee Height: A Novel Approach to Assess Dynamic Postural Control Independent of Lead-limb
Published on: August 30, 2016
A novel theoretical framework for the dynamic stability analysis, movement control, and trajectory generation in a
1Department of Systems Engineering, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA. kxiqbal@ualr.edu
Journal of Biomechanical Engineering
|December 3, 2008
Summary
This study models postural control using a neuromusculoskeletal system, finding that controllers are robust and adaptable. Reduced proprioceptive feedback significantly impacts stability and movement, highlighting the importance of sensory input.
Area of Science:
- Biomechanics
- Neuroscience
- Control Systems Engineering
Background:
- Postural control is crucial for human movement and relies on complex interactions between musculoskeletal dynamics and the central nervous system (CNS).
- Previous models often simplify the intricate interplay between biomechanical factors and neural feedback mechanisms.
Purpose of the Study:
- To develop and analyze a simplified neuromusculoskeletal model for characterizing human postural control in the sagittal plane.
- To investigate the role of proprioceptive feedback, muscle properties, and neural latencies in stabilizing the human body.
- To analytically synthesize stabilizing controllers for a multi-segment biomechanical model.
Main Methods:
- Developed a planar four-segment neuromusculoskeletal model incorporating Hill-type muscle models, active/passive stiffness, Golgi tendon organ, muscle spindle feedback, and neural latencies.
- Implemented proportional-integral-derivative (PID) controllers to represent the CNS analog for each degree-of-freedom (DOF).
- Performed analytical synthesis and simulation analysis to evaluate controller performance and robustness.
Main Results:
- The proposed model and controllers demonstrated effective disturbance rejection, trajectory tracking, and robustness against feedback latencies and torque perturbations.
- Controllers showed flexibility in adapting to changes in musculoskeletal parameters.
- Sensitivity analysis revealed that limited or absent proprioceptive feedback drastically reduces stability margins and available stabilizing parameters, leading to oscillatory movements.
Conclusions:
- The analytical synthesis of PID controllers is feasible for multi-segment biomechanical models.
- Proprioceptive feedback, muscle stiffness, force feedback, and physiological latencies are critical determinants of human motor control.
- The model provides a valuable framework for understanding the fundamental mechanisms underlying human postural stability.
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