The ability of the motor system to respond appropriately in the presence of disturbances is a fundamental property known as impedance. Specifically, impedance relates a dynamic positional displacement to the corresponding torque about the joint. Many interesting studies investigating impedance have been published that elucidate numerous properties of motor control. However, there have been no studies that explore the dynamic impedance of lower-limb joints during dynamic tasks. In this study we propose to determine the dynamic impedance of the ankle during walking. We will use a custom built robotic platform to perturb the ankle about its center of rotation and measure the ground reaction force. Using mechanics, we can determine the torque about the ankle during the perturbation, which establishes the input (angular position displacement) and the output (torque) to be used in a system identification technique. We will employ a quasi-static, linear identification technique to determine the impedance of the ankle, subsequently analyzing the impedance in terms of mechanical components.
The objective of this project is to determine the changing mechanical properties of the ankle while walking. This will shed light on how the brain controls the joints during dynamic tasks as well as have clinical significance. Using a combination of traditional and specialized engineering tools we can pave the road for the clinical use of these properties.
| Rouse, Elliott J; Hargrove, Levi J; Perreault, Eric J et al. (2014) Estimation of human ankle impedance during the stance phase of walking. IEEE Trans Neural Syst Rehabil Eng 22:870-8 |
| Gregg, Robert D; Rouse, Elliott J; Hargrove, Levi J et al. (2014) Evidence for a time-invariant phase variable in human ankle control. PLoS One 9:e89163 |
| Rouse, Elliott J; Hargrove, Levi J; Perreault, Eric J et al. (2013) Development of a mechatronic platform and validation of methods for estimating ankle stiffness during the stance phase of walking. J Biomech Eng 135:81009 |
| Rouse, Elliott J; Gregg, Robert D; Hargrove, Levi J et al. (2013) The difference between stiffness and quasi-stiffness in the context of biomechanical modeling. IEEE Trans Biomed Eng 60:562-8 |
